Yesterday I was using my IIgs and around the time of a reboot, I noticed horizontal lines looking like a comb at the top of my screen (I later found out this is called "folding over" in CRT terms. i used the vertical size adjustment on the monitor to get rid of them, but then noticed I was left with an image where things looked squished vertically, and the image seemed to be off center. There was a larger blue border at the bottom than top.
Thinking something in the vertical deflection failed in the monitor, i grabbed a spare monitor (that was previously adjusted for this IIgs) and hooked it up. I had the same folding over issue. I tried a different, thicker monitor cable, no change. I then hooked up my color IIe monitor to the composite jack. While this monitor did not show any fold over symptoms, it was clear the top part of the screen was getting clipped off and not centered properly (I never really used composite on the IIgs before, so I'm not 100% sure exactly how the image should "fit" on the screen compared to the RGB - but this doesn't seem right).
Given that multiple RGB monitors, cables, and composite seem to be exhibiting the issue, I can only assume something went wrong in the IIgs video path. I'm really hoping maybe some passive part went bad/out of spec some how. But I really don't know video circuits, so I'm hoping someone here might be able to help. Both the IIgs PSU and mainboard were recapped about 3 years ago. All the monitors used in testing had also been recapped at some point in the last 3 years as well. It is a ROM3 (if it matters) and a schematic of the ROM3 is available over at Reactive Micro.