Horizontal Hold issue on Neotec NT-500DX

[twistedsymphony]

I recently picked up a DDR machine with a Neotec NT-500DX monitor... the monitor is not original to the cabinet (evident by the fact that all of the video connectors on the harness have been cut and adapted by hand to the monitor.

When I got it the monitor had a horizontal tear across the top of the screen:


after a few hours of use the tear turned into a full blown loss of the horizontal hold...

This being a digital monitor there doesn't appear to be any way to manually adjust the horizontal hold.

I'm fine with soldering, I've done cap kits and flybacks before, and I know my way around digital electronics, but when it comes to analog stuff (like video signals and voltage control) I'm at a complete loss. I managed to find a schematic for this monitor here: http://arcarc.xmission.com/PDF_Monitors/Neotec%20NT-500DX.pdf though I really don't know what to look for.

if anyone has any advice on how to fix this issue I'd love to hear it.

Thank you