Scrambled picture out of a Light Sixer

[oldskoolboarder]

Helping a friend fix their Light Sixer.  I hooked it up to my OLED and without a cartridge, I get random white pixels on the left side of the screen.  When I use different cartridges, I can get random colored pixels on screen.  I know 'something' works because the sound from the games appears to work, when I used the Asteroids cartridge, I was able to hear the correct background sound.

 

Now I'm trying to figure out what's the deal w/ the picture.  I have access to an iron, DMM and single channel scope.  Not really sure where to start.  Any guidance?  Thanks in advance.