If RAM test is passing, could be a WPC DMD controller board problem on the interface from the video RAM to the ColorDMD. If you can swap DMD controller boards with JM, you can see if the problem follows the controller board.

I don't think it's ROM corruption because the error is in different locations on the two TOP ANGLERS photos. It's possible that it could be a poor connection to the ROM (like a bad socket or cold/corroded solder joint). But surprising if you're not seeing other problems.

The most likely culprit is a ribbon cable connection on the wide cables that run from the MPU to the audio and video boards. But since you've tried replacing ribbon cables and RAM test is passing it's a little tougher to isolate.

Swapping components between similar games is usually the easiest way to narrow it down. You can also try moving the ColorDMD to JM to see if the problem follows the ColorDMD.

Glad you found it. Take a look at the headers on the board. Could just be a poor connection that you can repair. If it's a logic issue, probably need to contact Rottendog for help.