AOC Traditional TV Vertical Output?

[WolfMama]

Hello. We have an old AOC Traditional (picture tube... CRT?) TV. It has an awesome picture, and has been through a lot! We'd REALLY like to repair it.

I'm not sure if this is the model number, or not. The front says "VST-600"

In any event, it suddenly lost picture to snow effect. We began to tinker with it, and found that if we play around with the V Hold button, it seems to resolve the problem. But, it returns after the TV has been off.

Is this something to do with the Vertical Output? Exactly what would need to be fixed/replaced, and how?

Also, if anyone has a manual for this TV, we'd appreciate it. I didn't find one on the search.

Thanks!