The tempered glass on pinball machines is thick, heavy, and amazingly durable stuff. Though it may cloud or discolor over time under seriously smokey conditions - and it's not immune to chips or breakage - for the most part the only maintenance it will need is an occasional swipe with some window cleaner.
There may be occasions when you need to get onto the playfield, however, and keeping in mind that these are the occasions when the glass is most likely to be damaged, it's important to understand how to remove and replace the glass safely. Specific directions for removing and replacing the glass will be part of your owner's manual. Some general guidelines apply to nearly all pinball machine glass, however. The glass is heavier than you might expect, and you'll want to have a clear space on the ground before you start taking it out, because you'll need two hands. Having an unfolded carboard box on the floor (lying flat) or several rolled towels to place the glass on is a good idea, and a must if you're going to be setting the glass on a concrete floor.
Generally speaking, getting the glass off requires getting the coinbox/front panel open, using the key. Once inside the bottom cabinet, near the top frame of the coin box will be some kind of a mechanical lever, usually underneath the metal trim at the very top front edge of the machine. The lever will release the trim from the frame, loosening the pressure holding the glass down and allowing it to slide out towards you, down the slope of the glass towards the pinball drain. Be ready to catch it if it starts to slide, something older machines especially may be prone to. You should be able to do this easily enough because you're probably standing in front of the machine in order to flip the lever. DO NOT LIFT UP when sliding the glass out; pinball glass, like all other glass, does not bend so much, and lifting up before the glass is completely free of the side grips will place enormous fracture stress at the point where the glass is still retained inside the grips; even a child could easily exert enough upward pressure to break the glass when it's two-thirds of the way out, and since it's tempered glass it won't just break, but will explode into a shower of glass particles that might be pretty if they weren't the sound of money disappearing.
Putting the glass back in is the same operation in reverse, and this is pretty straightforward. Be careful not to drag the end of the glass on concrete when you're picking it back up, and you may want to use a towel against the glass to push it fully in place once it's in the grips, rather than your hand, which will leave a big handprint behind. If the machine has a release lever and it closes with the glass in place, then the glass is seated; if the lever won't close then try pushing the glass up a little further.
Wholesale replacement of the playfield glass is an expensive proposition; tempered glass is costly, and getting a replacement sheet of pinball machine glass shipped/transported to your location may be more costly still. Another special consideration is when a breakage of glass has caused a shower of glass pieces into the playfield, generally because of something falling onto the glass from above. It's not common, by any means, but it can happen. Under any extreme condition like this, a reliable service provider should remove the debris and replace the glass to avoid additional damage to delicate internal parts.
If you'd rather skip the hassle and leave the work to insured experts, you can get in touch with us at TILT AMUSEMENTS to take care of maintenance, machine tune-ups or larger system restoration projects. We can help you with the glass, and can help you find a local source if you're outside our driving distance and you need to repair or replace glass. If you need any glass service, give us the details in our maintenance form below.