I have two Cadet's, nickel. One with original grooved glass, the other with plain plate glass. The coins will stack on each other with the plain glass although they will move up to fill the tube or jackpot. The grooved does not, coins stack and move up singly. I need to examine the grooved, or "channelized" glass, see if a picture shows the difference.
Actually the glass is 3 pieces of glass bonded to the base glass, Left side (with jackpot load) is 1/2" wide, space/groove is 5/16", Right side is 1 3/4" Total 2 5/8 wide,5 5/8 long The bonded sections are 1/16 thick, main glass also is 1/16 Measurements by ruler, but very close.
Hope it helps, I have no idea why it works other than allowing the raised faces of the coin to slide freely
I had a piece of lumber fall from a rack and smash that glass while the mech was sitting in the bench below. I just assume the groove is to let the fingers lifting the coins to move easier in the escalator.
I had taken a glass blowing class some time later and asked one if the instructors if it would be possible to fuse three pieces together. This was the result. Not clear but dimensionally correct. I suppose you could just use glass glue to do the same thing.
I still haven’t installed it on the mech but I think It will work. Dont know what the small square hole is for.