NEC Accusync 120 21" monitor with intermittent size problem?

This can be mostly from the power supply not being stable, or the HV multiplier module is going defective.

You can verify the power suppy, by monitoring its voltages with a DVM to start with. If the supply is stable, a new HV multiplier module should be tried. If I remember correctly, this module is part of the flyback assy.

It may not be worth to service this monitor.

Jerry G. ======

I have just found where the problem reside. behind the flyback and close the board at the back, there is a little added cct board when I move it, the size changes. I suspect the problem reside there.