Who knows about arcade repairs?

Hi. So I got the chance to work on what looks to be a 1980s Midway Ms Pac-man arcade cabinet. According to the owner, it worked fine until every once and awhile, you would need to hit the cabinet for the screen to clear up from random game trash, if that makes sense. But now it has gotten to the point of just showing a screen of trash at boot. I have researched a bit into it and I could be on the right path but I'm no pro at this stuff. From what I can tell, it isn't rebooting so the regular board works I think. It looks like it has a Ms Pacman Aux board on it so I am wanting to say that it could possibly be a bad cable from the main board to the aux board. From what I can find, you can supposedly take the CPU chip from the aux board and put it in the main board and if it works correctly, though it will show a odd looking pacman, then the main board works. Does anybody know someone who works on these things that could lead me on the right path or possibly help? Thanks in advance. If the photos show up, this is what I'm looking at.