Galaxian ship disappears or changes sprite randomly

[Maxxarcade]

I am working on a Galaxian that plays normally, aside from the ship randomly going invisible or changing to one of the explosion sprites.

The CPU and character ROM sockets are new, and I cleaned the legs on them as well. I figured I would try swapping the character ROMS first (they are the masked type), but I was curious if anyone else has seen this issue.

The frustrating part is that it won't do it again, now that I'm trying to troubleshoot it. I also tried running the test ROM, and everything passes.

 

[HudsonArcade]

Test ROM can only test the RAM... it can't "read" back what graphics are drawn to the screen.

The player's ship is drawn with background characters and sihfted right/left with line attributes.

If the RAM test isn't picking up errors on 3F/3H, then the muxes at 3J/3K are the next think to check, but it could be something as simple as dirty/oxidized sockets/legs on the gfx ROMs.