What do you mean by "the glass itself"? The only glass I know about is the playfield glass and translite. Sorry if I'm missing something obvious, but I'm a complete noob when it comes to board work.
I found the cable connecting J22 to J3, is there a specific way I should test it? I was able to get continuity between the pin 26 point on the display board and a point on the CPU that traces to pin 26 on J22, so it seems like pin 26 is good on the ribbon cable. As far as I know the ribbon cable is original. Btw, if the ribbon cable was bad, wouldn't both displays have the issue? The same ribbon cable connects to both displays.
Another question, how were you able to determine that pin 26 would be the pin to check when the manual refers to the comma as using board pin #44?
Sorry for all the questions, but thanks for the help!