The Wells-Gardner D9200 continues to be a source of problems for me, despite the neckboards being modified per this service bulletin. Its no wonder these monitor chassis were recalled a long time ago.
You may remember me fixing this issue before when some of the colors would randomly stop and start working. But this time, rather than loosing colors, the Red gun seemed to be stuck on at 100% and wash out the other colors. I confirmed this by going into the digital controls and trying to lower Red to no effect.
Following the neckboard schematics I visually traced the Red signal pathway through the components, and spotted this bulging/blown transistor at Q203.
According to the schematic, Q203, which is a KSP2222A transistor, is what limits the Red signal, so I'm sure its the culprit in this problem. I placed an order with Mouser Electronics for a bunch of these, and a few more NTE2501's just in case. :)
[11/17/10 Update] Well that didn't fix it, so back to troubleshooting. :( [/update]