Pudwink
Please post scope trace photos for video, vertical drive and horizontal drive signals with the right settings (Time/Div and Volts/Div) so that we can be absolutely sure the signals are correct.
If we then need to look at the drive signals at the test points on the monitor’s PCB can you work from the descriptions I’ve provided in post #65? I don’t think marking up the top side view of the layout diagram would make things easier so I’m not inclined to spend time on it.
Alan