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@jcs @paulrickards vertical deflection issue for one. Ask about it on the Arcade Repair Tips podcast. Those guys know an awful lot about monitors.

@jcs As others have said, this is a vertical linearity problem. The vertical deflection waveform should be a linear sawtooth wave, but it this case it's not linear. There may be an adjustment for it in the vertical timebase circuit. It may be a coil with an adjustable ferrite core

@jcs "It's broken"

@jcs Pure awesomeness.

@jcs @paulrickards I have limited CRT knowledge, but that’s a failure of vertical linearity: lines far too widely spaced at the top, and bunching up towards the bottom. (Actually, on a second look, it doesn’t look like it is bunching up at the bottom; I think the sweep is starting out way high, above the top of the tube, which results in it ending far above the bottom of the screen.)

@jcs bad vertical linearity. This is usually adjustable. Check the back of the CRT.