I was still suffering from the terrible interference type problem I've had pretty much from the start. Even with the ribbon cables and the fancy new custom PCBs, i was still getting a very noisy signal. Anyway, after hours and hours of analysis, i think I've finally got it going pretty well. The secret was to create a signal loop of all the control lines. Ok, probably obvious to someone who knows about such things, but I felt pretty proud of myself when I came up with it!
Anyway, the result is, a very nice test pattern, no noise, no distortion. The pattern moves, which you can't tell from the photo, but i might put a clip up on youtube soon.