Jaleco board sync problem with Supergun

[Blaine]

I've had this problem for a few weeks now and I'm out of ideas.

I can't get my Jaleco Megasystem 32 boards to output a steady picture.

http://vimeo.com/1586628

I've tried two different MS32 boards and two different games on each board, same result each time.

My two MVS boards, CPS2, Kaneko Super Nova and standard Jamma boards all run fine. It's just this one board.

I've added an LM1881 to try and clean up the sync, it's had no affect (although I can tell it's working because the picture has shifted left on the monitor).

The closest I have to a clue is when I first fitted the LM1881 circuit, I tapped 5v directly from the power supply. For 1 second, as soon as I connected the wire, the picture came on and was stable. I'm not sure what this means.

Any help would be greatly appreciated.