UMK3 arcade board not outputing 'red'

My UMK3 board just stopped outouting red, as in the image is only made up from green and blue now. Any ideas anyone? And if so, is it fixable? Its definitely no the monitor, as the its just that one game, and just happened now, as in it was working fine with the monitor before.

Anyone? Cheers.

Dirty connector or a cracked solder joint? My money's on dirt/corrosion on the jamma edge.

Use a pink eraser on the jamma edge. If that still doesn't work then trace the red output back.

These boards are also very common as far as getting bent pins that short from being stored. Do a good overall look of the PCB for bent pins and cold solder joints.