I recently scored a vintage Donkey Kong Jr. cab. It worked beautifully for a few days, but the horizontal hold started to go on me while playing. I opened it up, turned the horizontal knob to the right and it was fixed. That held again for a few days, but the problem returned. Over the last few weeks I've been having to open it and move that knob ever more to the right. Now, I've finally reached the end of the line (as the knob will move no more to the right) and I'm left with a screen full of lines.
Is this the death of the monitor, or is there some magic trick I'm missing? Has anyone seen this sort of thing in old nintendo cab with a Sanyo monitor?
One note: I've also tried a Donkey Kong board in the cab and it has the same problem, so I know it's not the pcb side of things.