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Part 1: How Pinball Machines Work

Essentially, a pinball machine in the modern sense (i.e. with electrics and flippers) always works the same way. The difference is how much technology is in it to make it work. As I wrote in the "What is Pinball?" section, there are three types of machines:

purely mechanical - those machines have no electrical or electronical parts inside
electro-mechanical (EM) - these games have electrical parts inside, like flippers, solenoids and backbox scoring reels
solid state electronics (SS) - these are the machines we know today, with devices driven by solenoids on the playfield and electronical parts in the backbox and under the playfield to control the game with a microprocessor

I will leave out the purely mechanical games since they are of no interest to me. The question is whether you are dealing with an EM or an SS machine which is very easy to tell by just looking at the backbox. If there are digital displays in it, it's solid state. If there are scoring reels, it's EM. It's that simple.
EM machines don't use computer boards and a processor, they only control the game flow through switches and motors. It's all set up in a logic which gives the game a system to work after, so game rules can be formed and the game will always act the same way. Of course, solid state is nothing other than that except it is done differently, with electronics. Since most people are interested in SS machines and beginners probably don't have an EM machine at home, I will use my knowledge of SS machines and describe their operation here. However, a lot of the solenoid and electrical stuff is the same for EM games!

Part 1.1: Playfield

The playfield is the flat wood inside the cabinet you play on. It is made of very stable and hard wood which doesn't bend and is quite resistant to heat. Of course you cannot play pinball on bare wood, so paint and lacquer is applied on top of the playfield to make it all nice and colourful, and the lacquer adds a perfectly flat and smooth layer the ball can roll on. Of course, the lacquer's main job is protecting the paint. However, since everyday arcade play wears down even the lacquer, mylar was started to be applied in the 80s which pro-tected the playfield for years. If you get an 80s machine today and the mylar is still in good shape, you can be grateful because other-wise the artwork would probably have a few wear spots. Later, Diamond Plate was used to replace the mylar for added protection and durability.
The playfield is where the action goes on, but in general it is nothing more than the wood you play on. Everything built under and on it are solenoids and their items as well as plastics.

Part 1.2: Playfield Devices

Ramps, bumpers, targets, magnets, switches, the good stuff which makes the playfield playable! Many are driven by microswitches or magnetic coils (solenoids). Here is a selection of the most used pinball playfield devices.

pop/jet bumper:
This is probably the most well-known item in pinball history. Almost every game has bumpers. Their task is to bump the ball away with strong force, and if multiple bumpers are placed close to each other, this results in quite a couple of bumps by the ball between them. Bumpers make pinball exciting, fast and unpredictable. A game without bumpers often lacks this excitement.
At the same time, a bumper is one of the most complex devices. It consists of a so-called wafer which is a round coloured plastic ring close to the playfield, the bumper socket, the metal bump ring around this socket which is normally in raised position, a lamp inside the socket to light the bumper up, and a plastic decal cap. How does all this work together? Under the playfield, a magnetic coil holds two metal rods which are part of the metal bump ring and go from the top to the underside of the playfield. When the coil is energized, it pulls its plunger into itself taking the rods with it. This means that the bump ring is dropped from its raised position to the bottom at a very fast speed. If the ball is near the ring, the force of it coming down and the diagonal shape of the ring will drive the ball away from the bumper. Of course, this process must be triggered somehow. That's where the wafer comes in; it has a plastic pin going under the playfield which is loosely touching a plastic "cup" connected to a microswitch. If the ball comes near the bumper, it rolls over the wafer which has a few millimeters of space to the playfield. The wafer drops under the ball's weight, but only to the side which the ball rolls over. The pin under the playfield therefore moves to the opposite side, pressing onto the outer range of the plastic cup it touches. This triggers the microswitch which in turn closes the circuitry of the magnetic coil, it energizes and the bumper is activated. All of this happens so fast that it can be repeated in a matter of eyeblinks because magnetics don't use up material and can be charged very rapidly unlike motors.
Bumpers are probably the loudest items because of their heavy plunging. They used to be the primary point awarders in old games, but by the end of the 80s, they took a secondary role being placed at the outer side of the playfield and being there for additional instead of crucial scoring. Bumpers are often assembled in a triangular pattern because this leaves enough space for the ball to come out some-time. Many bumper systems also have a rollover lane system above them where the ball occasionally is bumped through. You can find it on many classic 80s games and such 90s games as Terminator 2 or Star Trek.
Note: there is a type of bumper that was used before the invention of jet bumpers ("active" bumpers) and died over the years after jet bumpers had become the standard. This "passive" bumper does not have any solenoid assembly under it and is merely a stationary column with a rubber ring around it, kind of like a post, only bigger.

standup target:
Commonly used on pretty much all games, this is just a circular bullseye made of plastic which is hit by the ball and closes a gold-plated contact right behind it. Standup targets are the simplest items you can find. The closing contact tells the system that the target was scored. Standup targets very often come in banks of two, three, four or even more targets. They are often used to "spell" a word or number sequence displayed on the inserts in front of the targets. Hitting a target turns on the light under its insert and the letter is "lit". Once all targets have been hit, the whole word is lit and you get the award.

drop target:
This is similarly complex as the bumper and difficult to repair, and that's probably why later pinball games avoided having too many or any drop targets at all. They were usually used on older machines and came in banks there as well, much like the standup targets. Their task is the same; score when hit and light the insert. However, to indicate that the target has been scored and prevent it from being hit again, the target drops under the playfield and is now inaccessible. Once all targets of a bank have been hit, they normally reset and you can drop them again.
The technical stuff needed to do this is complicated, but not inunderstandable. It all starts with the simple fact that a drop target is a long plastic part which goes quite a few centimeters under the playfield; you only see the top part of it. When forced a few millimeters back by the ball (or your finger if you like to test it), the mechanism holding it up is released and it drops down, all without electrical energy. The tricky part is recognizing that is has been dropped which involves so-called optical devices or "optos". It's a sender and a receiver LED which creates a light beam much like light beams used in elevator doors to keep them open when they "sense" that something is bet-ween them, or light beams in heavy security areas where "touching" the invisible beam leads to the alarm going off. The light beam under the drop target senses that the target is blocking it and tells the system that the target must have dropped. Now, there is also a mechanism using coils to reset the whole drop target bank, popping them back up above the playfield where they click into their holding mechanism again, waiting to be dropped another time.

spinner:
Well, it spins. ;-) The spinner is an old-school device as well, coming from the days where it was still used to score big. Nowadays a spinner is normally only a decoration device shelling out some thousand points and making a nice sound. It's basically just a metal plate with a decal sticker on it (remember the cool shiny hologram stickers that change colour and sparkle?) connected to a small wire which goes under the playfield and pulls up a gold-plated leaf switch. When the spinner spins, the unsymmetrical wire holding it in place drives the contact wire up and down like the wheels on a steam train and this opens and closes the contact under the playfield by pulling it up and releasing it repeatedly. Each spin awards points, makes a sound (bells on EM machines, electronical sounds on SS games) and maybe flashes a light (like on The Machine). The unsymmetrical wire also makes sure that the spinner always stops in the open contact position and never in "mid air" due to its overweight.

saucer / kick-out hole:
A saucer is called saucer because its shape makes the ball "fall" into it and stick there, much like a saucer would. Its task is to hold the ball after it rolled into it and kick it out again into a defined direction. Saucers are used to pause the game to play a sequence, like the selection of a random award. A coil under it triggers a popper made of a semi-circle metal shape which is turned upwards when the coil energizes and kicks the ball away into the installed direction.
Note: saucers are also sometimes called kickers because they kick the ball away.

sinkhole:
Sinkholes are a little more complicated than saucers. They have a metal "cellar" assembly under the playfield which the ball falls into. This assembly is shaped like a semi-circle where the ball comes down as if it was on a half pipe. It stops horizontally in front of a coil with a plunger extension which is pushed outwards in the reverse direction of the actual plunger which is pulled in when the coil is ener-gized. The machine knows that the ball has arrived in the horizontal part through a closed microswitch the ball lies on. Once the game decides to kick the ball out, the coil does just that and the ball flies back up the way it came in.

ramp:
Ramps have been on pinball playfields for a long time. There are (old) games that have no ramps, but most modern games have, especially 90s games. A ramp can be made of plastic or metal (Terminator 2 has both) where metal could actually be favoured because the plastic walls of the ramp often crack from the high abuse they take when the ball bounces between them. Installing metal ramp wall protectors at the entrance helps keeping the ramp healthy and cloaks existing cracks. Williams obviously knew this and installed such protectors themselves on certain machines including Terminator 2. Weird fact is, although Star Trek came after T2, they did not use protectors there even though the game has three plastic ramps and these are very often seriously damaged when you buy one!
How does a ramp work? Well, it does nothing more than lead the ball up to a higher level. The only thing a ramp needs to tell the system is that the ball crossed it. This is done by a microswitch connected to a metal gate made of thin wire which the ball levels as it passes through. Easy, huh?

loops & lanes:
These are no devices themselves, but they have a microswitch under them in an area the ball must travel to make the loop or lane shot count. The microswitch has a metal wire that goes to the top of the playfield and is shaped like an updown v so the ball can roll over it and push it down for a moment as it crosses the top of the v shape. This closes the microswitch and scores.

magnet:
Magnets are the really good stuff. 90s machines love them, but they were there already way before. The most memorable magnet is probably featured on Black Knight (1981) and Black Knight 2000 (1989) where it is incorporated in a feature called Magna-Save™: if the ball threatens to drain through the outlane the magnet is under, simply press the Magna-Save button which is located behind the flipper button. The magnet will be energized and force all of its power through the wood of the playfield, affecting the ball and grabbing it for a few seconds until it releases the ball into the inlane. This kind of under-playfield magnet is very strong and the coil needed for it is respectively large. I've read that a few Black Knight machines have wear spots directly where the magnet is because it held the ball so strongly! I've also seen system-activated magnets on machines like Tales of the Arabian Nights where the ball is held in a vertical plastic ring on top of a ramp. It looks as if the ball was floating inside the ring!

ball popper:
Apart from saucers which kick the ball out at a low force, there are also dedicated ball popper assemblies to shoot the ball up into a metal wire guide or transfer it from one location of the playfield to another. Those poppers are simply coils with a reversed plunger like in a sinkhole, but the ball lands on top of the plunger which is covered with a cup made of plastic or rubber. Once the ball lies there, it presses down the plunger a bit due to its weight and this triggers a contact telling the system that the ball is in the popper. You know what happens next.

slingshot:
Usually located above the flipper lanes and shaped triangularly, a slingshot does nothing more than count a few points and make the game more dramatic by randomizing the ball movement even though it's so close to the player's control, the flippers! Two slingshots are placed to the left and right near the flippers so they can kick the ball forth and back for an uncertain time. This can often lead to a drain through the outlanes.
A slingshot works with a rubber ring which is pulled around the star posts making up the triangular form. The rubber contacts two gold-plated blades on the kicking side. Those blades are pushed back when the ball hits the rubber and bends it inside the slingshot. The blades in turn close the contacts they are part of (one closed contact is enough, there are two contact blades for better balance along the rubber) and the coil under the playfield is energized. It pulls the plunger in which links up to a kicking assembly that kicks the rubber out-ward and takes the ball with it at strong force.
Slingshots can sometimes be found on other parts of the playfield, e.g. near the bumpers on The Machine to keep the ball in the area for a longer time.

flippers:
Flippers are playfield items as well. However, they are complex enough to write an own section about them.

Part 1.3: Flippers

Flippers are the trademarks of pinball. Time to learn how they work.

In general, flippers rely on some of the strongest coils available. They need extremely high power to be able to catch and shoot a metal ball with accuracy and precision. This is why the modern Williams and Bally coils use 50 volts, more than the smaller coils used for other devices. But the power of the coil is influenced by some other components in the flipper assembly, so cleaning them is essential to keep the flippers powerful.
A flipper works like this: the coil has a plunger with a return spring which secures that the flipper returns to the home position when not in use. When the flipper button is pressed, the coil is energized and pulls the plunger in which has a movable link attached to it. This link is screwed to the flipper itself and pulls it up. But that's not all there is to it. There is also the end-of-stroke or EOS switch.

I explain the EOS switch in the glossary, but I want to do this again here to a little more extent. The EOS switch is always installed in the flipper assembly, no matter what system the machine uses. Basically, the EOS switch tells the system that the flipper is in the "up" posi-tion and diverts power. The coil used for the flipper has two power sides, one for high power which pulls the flipper up with full force, and one for low power which is activated by the EOS switch to hold the flipper up. Why is this done? Because holding the flipper for seconds with high power would burn the coil. It would just keep pulling and pulling with full force which would make it overheat and burn since the high power side is too much for the material to handle for more than a few seconds. So, it is critical that the EOS switch is there, working, and correctly adjusted, except for Fliptronics™ flippers where the electronics can compensate for the broken switch. The question now is, which system is your pinball machine using, and of what kind is the EOS switch?
Pre-WPC and early WPC systems use a switch which is normally closed and opens shortly before the flipper reaches the upper position. Opening it diverts power from the coil. Since the switch opens every time you flip, the contact plates which are made of Tungsten mate-rial will start to feature arcing from the high voltage running through them. Arcing causes dirt, dust and therefore resistance. The more you play, the more resistance the contacts get which means they don't lead as much power through as they would if they were clean. This is the primary reason for weak flippers. If you have flippers that you feel could be a knack stronger, clean the EOS contacts. I still don't know whether I do it correctly since I tried it with three machines and never got a really good result, however I know people who can clean them with enough patience so that they gain extremely much power from used-up flipper assemblies. They say you need to use a small metal file or fine sandpaper (400 or 600 grit) or both while pressing the contact plates together so you get an even surface that will fit completely together and lead all the power there is. As I said, I never seem to get it right, but it's the way the pros recom-mend. If cleaning doesn't help, simply replacing the worn EOS switches can be a very good (and inexpensive) repair.
A note of warning goes to the pre-WPC machines which have a second switch next to the EOS switch. This switch is for the switch matrix and tells the game that the flipper has been activated. It closes when you flip while the EOS switch opens. When you clean or adjust the contacts, turn the machine off because if you happen to get the two switches together, this means death to the switch matrix which would get full flipper power from the EOS switch!

The whole situation looks different for Fliptronics™ WPC machines (1992 and later). The EOS switch changed in design to be a nor-mally open switch which closes upon flipping, and this switch transports low signal voltage instead of full coil power. This reduces the arcing and thereby the cleaning effort. Plus, the contacts were changed from Tungsten to gold-plated, which is even better. Gold-plated contacts have close to no arcing and therefore don't need cleaning except for a dry wipe with strong paper. Do not file the gold-plated contacts because this will remove the plating and the contacts will be useless. If a Fliptronics EOS switch breaks, the flippers will still work fine because the Fliptronics board can compensate for the missing switch signal and turn the high power side off by itself, however the EOS switch does enhance the precision of the flippers and should be working for optimal results.
For more info on how exactly flippers work and more tips on cleaning and caring, I highly recommend Marvin3m's pinball repairing guides which have a dedicated section for flippers in each guide, from EM machines to Pinball 2000.

Part 1.4: Lamps

Pinball machines use 1 watt or 2 watt lamps numbered #44 (2 watts) or #47 (1 watt), but while these metal-socketed lamps were almost exclusively used in 80s machines, they were mainly replaced by #555 lamps which have a glass socket. It was probably done because glass sockets are easier to install, plus it reduced wiring under the playfield because glass socket lamps are always installed on small lamp boards which connect a series of lamps and have a single connector for information and energy exchange. Terminator 2 has almost no metal socket lamps anymore, but a lot of lamp boards which have glass socket lamps installed. The problems with glass sockets are that they break easier than metal sockets and that the boards need to be repaired or replaced if they are damaged, whereas a wire going to a metal socket lamp can easily be exchanged. However, disassembling and reassembling a machine for a playfield ex-change or maintenance is far easier with lamp boards instead of hundreds of wires.
In general, a pinball lamp can hold for years, depending on the condition of the environment and the time of play. Pinball lamps do not break from blinking as opposed to big room lamps which your mom told you not to turn off and on all the time. You could say that pinball lamps were made to blink because this is what they do most of the time. Don't confuse them with the "blinking lamp" though since this is a special lamp for a few pinball games which blinks all the time by itself!
Also, pinball machines use flashers, larger lamps which flash very brightly for an instant when energized. Like the blinking lamp, flashers cannot burn constantly, they can only flash for the same blink of an eye. They can be controlled by the system to flash faster and slower though and are an essential decoration in modern pinball machines. Flashers were introduced by the appropriately-named game Flash by Williams in 1980, I believe.

If you wonder what part of a pinball machine eats most of the electrical energy you're going to spend for your game(s), the answer is: the lamps. The magnetic coils, motors and displays need energy, however they are not turned on all the time like the lamps, and I've seen a real-time comparison between a machine in attract mode and the same machine being played where the watts counter raised only slightly. A pinball machine usually takes between 200 and 300 watts, so it's comparable to a modern PC.

Part 1.5: Electronics

Since I am not an electronics guru, I'm the wrong person to write about the boards inside the backbox. I'll give a rundown of their func-tions and some hints on assembly instead.

Depending on the system of the machine, the boards vary. Some systems unified them all in one board, some had five. In general it can be said that a solid state pinball machine needs the following units to be controlled:

- a power or solenoid driver board which controls the energy flow to all solenoids and/or lamps (older machines use lamp driver boards)
- an MPU which is like the motherboard of a PC, has the microprocessor and the ROM chips on it
- a sound driver board which controls the audio
- a display driver board which controls the video

Pinball 2000 games have a real IBM personal computer inside instead of the custom-made boards of earlier generations.

If a board breaks and needs replacement, it's often possible to interchange boards between different machines as long as they use the same system. Especially System 11 and the same WPC generations can be swapped. This is possible because the boards have the same generic architecture and the game specific details are on the ROM chips which can be installed on the swapped board to "convert" the board to the other game. Also, the connectors have enough sockets to fit on. When I assembled the backbox of my Terminator 2, I com-pared the boards with The Machine's boards because they are of the same WPC generation. I noticed that the same sockets existed on both boards, but the connectors had different positions because the game required them to be seated elsewhere on the same board.
If the need arises to disconnect the cables from the backbox (e.g. for transportation of the single backbox and cabinet), you can use the J- and P- numbers on the boards which are printed on the socket of each connector. Simply write the number on the connector using a waterproof pen and you'll reassemble the whole thing in no time. But how to read those numbers right? Williams' WPC manuals say this:

"Each plug or jack receives a number that identifies the circuit board and position on that board that it connects to. J-designations refer to the male part of a connector. P-designations refer to the female part of a connector. For example, J101 designates jack 1 of board 1 (a Power Driver Board jack); P306 designates plug 6 of board 3 (a Display Driver Board plug). Identifying the specific pin number of a con-nector involves a hyphen, which separates the pin number from the plug or jack designation. For example, J101-3 refers to pin 3 of jack 1 on board 1."

Of course, this counts for WPC games only. I'm not sure how it works in a System 11 game, but you get the idea of the system from this example.

Part 1.6: ROMs

ROM stands for "read-only memory". It's a chip on the MPU board loaded with a program and game content like game rules, audio or display effects. Normally these things are separated on a handful of ROM chips. Should a chip break or the board need to be replaced, the chip(s) can be exchanged by plugging in a new one where the old one used to sit. It's really plug and play.
The files contained on the chips are often referred to as ROMs as well. You can find pinball game ROMs (small letters are commonly used) on the Internet to upgrade your machine or use the ROM in conjunction with an emulator on your PC. Upgrading the ROM files on your machine can reward you bug fixes and better gameplay if the difference of the version numbers is big enough. It doesn't really matter whether you run the last version L-8 or L-7 as they probably won't have a lot of differences, but if you still have L-3, an upgrade could be useful. You'd need someone with an EPROM burner though and an empty EPROM chip you can burn the ROM files on. Some people still do this with the old C64 computers. I don't know anything about the burning process so I can't tell you what it involves.
So what does EPROM again stand for? It's an "erasable and programmable" version of a ROM chip, so that means you can erase the existing content and store new files on it. PROM chips on the other hand cannot be erased once they are burned.

The ROM system actually has an OS, like a personal computer running DOS, Windows or Linux. Of course this system is very basic, but ever since the early 80s it provides the operator with a setup structure on the display(s) which is used to set game-specific and technical options or check the bookkeeping, e.g. the total number of games, balls, extra balls, credits, collected game features etc. Ever since System 11, the setup is done in a menu with chapters to easily navigate the options, especially on WPC models where you can go up and down between main categories and sub-chapters.
Perhaps the most interesting option of all is the "free play" option in System 11 and newer machines. Many people who sell pinball machines and aren't collectors themselves will tell you that the game needs money to play, "but it can be taken out again from the cashbox" or "the credit switch can be manually pressed". Setting "free play" in the menu to on will erase the need for inserting coins or pressing credit switches. The game knows it doesn't need money to operate and thus all players need to do is press the start button to launch a new game!

Part 1.7: Tilt Mechanism

The tilt mechanism is actually three mechanisms, one for each way of cheating. On many machines there is the slam switch which is a leaf switch contact inside the front door of the cabinet. If the player hits the machine from the front to cheat, the switch closes due to the vibration and the game is aborted (slam tilt). The far more known tilt version is the shake tilt, which gives out warnings if you start shaking the machine too hard to keep the ball in play. Once a number of warnings has been ignored, the game lets the ball drain by deactivating all solenoids, switches and the flippers. The warnings and the tilt are triggered by a metal pendulum inside the cabinet, at the front left. This pendulum starts swinging when you shake the machine. Once it contacts a metal ring around it, the warning or tilt is triggered because the pendulum and the ring close the circuitry needed for tilt activation. It's a simple mechanism, but it works effecti-vely. Depending on how the ring is set up, some machines have a tighter tilt than others, but you can change this with your own game by reshaping the ring (it can easily be bended since it's made of soft metal).
The third mechanism is the same leaf switch contact like for the slam switch, however this contact is installed under the playfield and is intended to keep the player from punching the playfield - however, is there a sense in that, seeing that we have a glass over the play-field? :-/ Probably this is why it's not featured on WPC machines.

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Part 2: Basic Things That Need to Be Done

When I receive a new pinball machine, the first thing I do is check the look. Is the playfield damaged so that it might cause problems when playing or simply when turning on the game, i.e. are there any broken contacts or missing/damaged items? The next thing to do is open the backbox and check the interior, unless you know from the seller that it is working. If you have no guarantee that it works, don't turn the game on without checking! The backbox contains the boards, the CPU, the batteries and the displays and all of those could cause trouble when turning on a game that isn't working flawlessly.
The most important thing to look for are the batteries. If the game features the common three AA batteries in the holder, check that these have contact with the metal plates and that they did not leak. If a battery leaked, the result might be that alkaline fluids have glued to the boards or the CPU, which will not! allow the game to work correctly! In fact, if you turn it on with battery alkaline on the circuits, this can lead to a lot of problems. Removing the alkaline is possible by extracting the board(s) and washing it/them with water and vinegar, then after drying bathing them in a little isopropanol so that the water will be completely washed away. When dry, reinstall.

Older games from the early electronics area often have a single battery that is fixed to the board. This battery will most likely have leaked when you get the game unless it was already cut off or replaced. In any case, there are options you can take to replace these fixed batteries. Look for more info on Marvin3m's pinball repair guides.
If the boards look good and there are no problems on the playfield, you can be extra careful and take the glass off, open the playfield and check the wiring, especially the power wires and connectors (also check the connectors in the backbox!). Any brown or black and crispy connectors mean they are burned and will probably not work anymore. These need to be replaced. Again, Marvin3m's guides provide great help in doing this.

After this routine check is done (or if you know the game's in good condition and you left the check out), turn the game on and watch it go. If it works, the next hour will be filled with excitement.

From now on you need to operate your game, not just play it. Operating starts with the setup. If you got yourself a nice Williams machine with alphanumeric displays or a dot matrix display, open the coin door and press the setup button (refer to the game manual to know how the button system works for the generation of your game) to access the menu system. From here you can configure the game, for example set free play, change replay awards, read out game statistics and so on. I always do a factory reset when I get a new game so I can make sure that the game records only my personal statistics and I play on factory default rules (which might have been changed by earlier users).
Operating means a lot more though. You should routinely check the playfield for any problems, broken parts, loose screws and burnt lamps. Rubber and lamp exchange is discussed in the next part. And while cleaning is a basic thing that needs to be done too, it is a little too specific to not write an own part about it.

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Part 3: Cleaning & Caring

After a number of games on a new machine I usually get the feeling that it could all be better. When this happens, the first thing I do is check the playfield condition. Are there any big wear spots, are the inserts coming up, or is it simply dirty and can easily be cleaned? Often it will be dirty AND feature wear, so it's up to you whether you enjoy the game so much that you want to keep playing for a while (in which case I'd clean only and leave the wear spots for later) or you want to make it shine again as good as you can.

In any case, the most basic thing you need to do after a while, be it a new game or a game you've got in your collection for a while, is clean it. This involves cleaning the playfield itself, the ramps, bumpers, targets and other devices that have direct ball contact, plastics, lamps and the glass.
The easiest way to clean stuff is using isopropanol, a synthetic alcohol you can buy in any pharmacy. Watch the percentage though since the usual stuff (70%) will be fine to clean plastics and everything else, but the hard stuff (99%!) is suitable only for tough dirt and not risk-free when cleaning plastic parts (artwork might be damaged). The big advantage of usual isopropanol is that it is thin and trans-parent, it's not dangerous to your skin as it's normally used in medicine to desinfect body parts, and in return it can remove dirt and ball traces very effectively. Lacquer is not damaged by it and even the original paint under it doesn't get washed off so easily (be careful not to have isopropanol on the same paint spot for too long since this will dissolve paint). Plus, this stuff will get any wax and other grease off the playfield, making it suitable for polishing, rewaxing or painting (before waxing!).
If the playfield has Diamond Plate lacquer on it, you probably don't even need to polish it since the lacquer takes months to years to get a rough surface. Normal lacquer without mylar will probably look rough or layered with a gray shade if the game is older or wasn't cleaned for a while. In that case, polishing will work wonders most of the time.

Mylar is a special condition to discuss. If the mylar doesn't have big scratches or lots of bubbles, it's probably best to leave it on the playfield, clean it and try a wax-free polish on it to make it smooth. If the mylar starts to dissolve or if it's made of parts and not a single factory-installed coat, you might consider lifting the mylar off the playfield, which does mean risks - again, there are lots of guides to proper mylar removal, some of which are up in my "Links" section. This is not strictly a "basic" thing though; I just wanted to clear that a mylar playfield might require a little more than basic work to keep its good condition.

Many people use Novus to polish their playfields although Novus is actually a cleaner for plastic parts. This means you can use it to clean ramps and plastics just as well as with isopropanol. Novus-2 is the preferred polish for playfields. Of course you can use practically any car polish and wax to clean and coat your playfield, however there are of course brands that work better than others. Then again it is questionable whether all of these brands can be found in your local store. The known to be best polishing and finishing brands are 3M's Finesse-It and Perfect-It, but these can usually not be found where you can get "usual" polish and wax, plus they cost bucks. The results I've seen on photos are spellbinding, though.
Some people put their ramps and posts into the dishwasher. I've tried it with star posts and it worked beautifully, but I wouldn't dare washing my ramps with it. Cleaning ramps with isopropanol and maybe polishing them a little to get off any ball traces works best for me. The same goes for plastics.

So in short, to do a basic cleaning of your playfield, do this:

1. Disattach all items and plastics that are in the way.

2. Clean the playfield with isopropanol. No damage occurs to the lacquer or mylar, so you can leave a drop on the same spot to sink in to get tough dirt off. Be careful not to do this with unprotected paint where the lacquer has worn off.

3. Clean the ramps and plastics as well as metal parts with isopropanol, but be careful not to damage artwork. It's better to use 70% or lower isopropanol here instead of 99% (which is best for playfields). Alternatively, use Novus to clean plastic parts.

4. Put your plastic posts into the cutlery basket of your dishwasher and have a go. Try to use tabs with little salt percentage, otherwise your posts will get little white dots in the notches.

5. If you wish, you can put your metal parts into a tumbler (a device that polishes metal using granulate) to get them all shiny. Takes a day or two, though, and costs you money for the tumbler. If you can live with ball traces, simply clean the metal parts with isopropanol or a more aggressive cleaner (since it's metal).

6. With all the parts off, if you feel the lacquer or mylar is not smooth enough or looks gray, use a standard car polish and a soft towel or a polishing adapter for your drilling machine to polish the playfield. If you do it with the machine, make sure you go at it so that you will not generate a lot of heat on the same spot; it might damage the lacquer. Rub all the polish away until you see a clean and shiny surface. You can also use Novus-2 to polish the playfield like many pinheads do, or if you want to spend money and have the best results, go for 3M's Perfect-It.

7. If you wish, you can wax the playfield which is especially good if it has standard lacquer which might have become thin with the years. Wax protects the lacquer like a shield for months or even a year before you need to rewax. Note though that the next time you clean the playfield, you can't use any cleaner on it since this will dissolve the wax (and you'd need to wax again). You can use standard carnauba car wax; it will get hard like a second coat of lacquer and make the playfield very smooth if it has been polished. Try to use high-quality wax which does not start to yellow by the time or else the playfield might get a yellowish layer after a while.
If the playfield has Diamond Plate lacquer, waxing is not really necessary, but using a combination of polish and wax like it can be found in many car stores gives great results. Make extra sure that you do not wax a playfield which has mylar on it; only wax the pure lacquer since wax doesn't stick to mylar very well and will travel on the ball surface instead, spreading across the rubbers and items.

8. If the playfield needs restauration and you feel that the lacquer is so bad that the playfield could be re-lacquered after restauration, you will obviously not want to wax the old lacquer, but take the necessary steps to prepare it for the new coat. There are guides about lacquering playfields, see the "Links" section to find them. Note that this is not cleaning and caring anymore, it's semi-professional restauration work and thus not covered here.

Caring does not only mean cleaning, it also means repairing and replacing stuff. The most basic things you need to replace from time to time are rubbers and lamps. White rubbers are the usual choice if you replace the old ones since white rubbers are much softer and fleshier and in turn have a better rebound. Black rubbers, which some people put on the 90s games (since these featured black rubbers when they came from the factory), are smooth and slick, have much less rebound and "kick" the ball harder than white rubbers, for example on slingshots.
Lamp replacement is easily done, you only need to know which lamps you are facing. See the first part of this page to find out about the lamp types. Basically you only twist out the broken lamp and replace it with a new one of the same type. You can do this relatively safely with the game turned on so you see which lamps are affected.

And if you need to repair stuff, check part 5.

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Part 4: Things Which Can Go Bad

Sometimes you did something that had a result you did not foresee, or the machine starts living by itself and starts doing things you don't want! In such cases it's best to turn the power switch off first thing, then take your time to check the game for causes.
You might  run into little problems like a broken device which is easy to fix. But there are a lot more things which can go wrong. The display(s) could (and will someday) stop working, the audio could start sounding like it has been chopped to bits, or the whole game locks up and won't work anymore at all. In serious cases, there might be shorts to the switch matrix, rendering the machine completely non-functional.

Of course, all of this doesn't happen without causes. If you keep your machine clean and regularly check for broken parts, you won't have any problems. But what if a machine you just bought acts stubborn? It's time to look for the root of the problem.

In any case, I cannot stop repeating how important Marvin3m's repair guides are! If you have technical problems, that site should be your first stop.

Things to note when you have a small to medium problem to minimize damage and costs:

- Check the contacts of the broken device. The cannon on my T2 didn't work when I got it, but it was a matter of contact adjustment.
- Check the wiring. Run the test sequences in the setup menu and see whether the solenoid responds; if it doesn't, the coil might have no energy, most likely because a wire dissolved from it or broke.
- Remember that solenoids are daisy-chained. If a bumper does not work, check the slingshots as they might not work too (just an example). If that's the case, a wire in the chain has dissolved from a coil and broke the whole circuit.
- Broken devices should be replaced, at least the parts that are broken (e.g. the coil). Leaving them like they are can lead to problems sooner or later. And of course it disturbs gameplay.
- Many newer machines will notice that something is not registered by the software and start playing the game in "best possible mode" which means that not working contacts and targets will be substituted by the software or disregarded so the game can still be played to the end. This is a technique Williams conceived in the late 80s to ensure that broken games still made profit until they were repaired.
- If connectors are burnt in the backbox or under the playfield, they are a risk of fire or short circuits. Replace them.
- A broken display does not always mean it's dead. It could be transistors, wires or pins. Don't throw a broken display away and check Marvin3m's repair guides!

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Part 5: Repair & Restoration

Coming soon.