Old Gottlieb System 1 backglasses had a problem in that the blue-green
display filter that was silkscreened on the backglass is easily damaged by
moisture or scratches. You can easily fix this by first carefully removing
the blue stuff with a razor. Any remaining residue can be dissolved with
rubbing alcohol. Be careful with the alcohol that you don't get it on
anything but the blue stuff, or you may lose part of your backglass
Go to a theatre supply house and ask for Lee Filters Theatre Gel #116
(greener) or #172 (bluer). Both hues are extremely close to the original
tint, and are difficult to tell from the original. They come is a sheet
about 24" x 18", so you can do many games with a single sheet. Cut pieces
from a sheet of gel to 1-3/4" x 6" and tape the gel on the back of the
backglass using a couple of small pieces of high quality clear mylar packing
tape. This tape won't cause problems with your glass, nor will it fall off.
New tips are welcome and encouraged. Tips will be credited to those who
contribute. If you would like to submit a tip click
For more information you may contact us by email, email form, or by phone at (801) 277-0888.