Bad green drive transistor on your neck board assuming that has a U2000/U5000 Wells-Gardner in it. Notorious issue with those.

Try turning the Green Gain, Green Bias pots on the monitor. I suppose those could be flaky as well.

Does your neckboard look like this?

wells-gardner-u2000-monitor-chassis_1_9d614c3bee0dd3d3a77770df57d03757 (resized).jpg

You might get a little shock. Haha.

If you’re any good at soldering, I’d just shotgun all of those color drive transistors (RGB). As you can see, the heat sinks are shit and they get toasted along with the traces.

Discharge the monitor by attaching an alligator clip to a large flat head screwdriver on one end and to the monitor frame on the other end. Lift the suction cup of the anode on the tube and stick the flathead under it to discharge and pinch the anode clip out of the tube. That’s the only thing that’ll give ya a real jolt if you don’t discharge it.

Retrofitting it for a consumer LCD screen is also an option since it’s medium res (?). You’d just need an upscaler and a cheap monitor from Best Buy. Fun little project!