I have a PVM20M4 with some issues.
Couple of time/seconds after power on the image is going in this weird state (See pictures)
When hitting (carefully) the screen, the tube or the canon.. it's back in a perfect state.. time after it's the same problem.
I thought it was more a problem on the neck board with a dry solder, but moving the neck is not resolving. It's like something in the tube or near the tube doing this interferences..
Do you have an idea of the problem or a way to look at it?
The video:
https://streamable.com/2sf95z
The images:





thanks,