Response from Jonathan: Pete,

It sounds like the Mario Kart 2 board is putting out a different frequency from what the monitor supports. It could be that the monitor you installed is a standard resolution (15 kHz) monitor and the Mario Kart 2 only supports either medium resolution (25 kHz) or VGA resolution (31 kHz). You could try looking for a switch or connector on the monitor chassis that allows you to switch the resolution but not all monitors have this capability. Another route to go is to get a video converter such as the Gonbes GBS-8100 that takes a VGA signal and converts it down to standard resolution. Of course, you need to figure out what resolution your Mario Kart 2 board is outputting so you can figure out what route to take in your repair.

Hope that helps. Thank you for your question and good luck with your repair.