X68000 Compact RedZone VRAM Issue

[costa]

Hi there.
Long time since I last visited this space, hope it still thrives.

Looking for some technical advice, I have a few X68000 and used to do basic repair (recap, bad connections) - onl simple fixes.

But My Compact RedZone has a VRAM issue, which is more complicated to diagnose and repair.

It looks mostly fine, but some graphics are corrupted in the backgrounds. Please have a look at the pictures below.









I am looking for some suggestions on how I can identify exactly where the problem is, since it might be a bad line, a bad ram chip, or maybe a capacitor. How can I test the parts such that I identify a failure?

Any ideas?
thanks