I've had that on 3 video boards. I never found out exactly what it was. The only people I've found to work on them has been El Dorado games. The first board I sent them, it had a crystal problem, so they replaced that and it fixed it. I then screwed up that board (long story), so I sent that one to them as well as another another messed up video board. On the first one, they had one of their techs work on it for 3 hours and still hadn't nailed it down. Since I really didn't want to pay the labor costs, I just told them to keep that board as payment. With the other video board, I think they just did a board swap and sent me another working one. I had a third video board at home that has the same video glitch. I never sent them that one as I wanted to keep one partially working board. So now, I have 1 fully working board set and another working CPU board and a glitchy graphics board. I know this doesn't help much with your issue, but it seems to be a very common problem that doesn't seem to have an easy answer. I have no idea how you test the crystal or who has them for sale (I know Bob Roberts has Atari crystals, but I don't think they're the right ones...maybe Mylstar?). There have been multiple reports of issues with El Dorado, but until someone else steps up, I don't see any other option. The first set I sent them, I think I was charged $80, which included return shipping, because it was a quick fix. Usually they'll attempt to try to fix it and if the cost goes above the cost of just swapping boards, they'll call you and just recommend the swap. Good luck, and let me know if you ever solve the issue.