Sega 32x black video

Hey all, I recently acquired the adapter cable to connect my 32x to my model 1 MD, but I can't get it to work correctly. The MD video comes through fine, but anything generated by the Mars hardware just shows black.

I've followed this repair guide cleaning and reseating the ribbon cables a few times, as well as cleaning all the edge connectors and slots:



This is the problem as demonstrated in Chaotix's colour test:



It's supposed to look something like this: http://info.sonicretro.org/File:Chaotixamycode.png

The audio hardware and passed-through video work, at least, so I can jam out



Any ideas? I'm tempted to just try my luck with another system since they're so cheap.