CV scrambled graphics (common solutions not working)

[Chupperson]

I have a ColecoVision with some scrambled but recognizable graphics. I've done the +5V RAM mod; I've cleaned the power switch; I've tested with a known working power supply (and the one I was using for it tests good anyway).

When a game starts up, the sprites have the right colors and everything but they're missing pieces or they pull up the wrong part of the sprite.

What other problems could be causing these results?

[NIAD]

Usually messed up graphics like you are experiencing means a bad RAM chip and the CV Tech Manual will give examples of the CV BIOS screen that will help pinpoint which RAM chip is the culprit. If it ends up not being a RAM chip issue, then maybe the VDP.

[nanochess]

There could be a scratch in PCB between VDP and VRAM.