Princeton Graphics 19" VGA monitor problem

[chazbeenhad]

I have a 19" Princeton monitor in my arcade cabinet. I am having trouble on and off with it where the black level or contrast will  flicker darker and brighter. Its only a flicker here and there and is very random. The display still looks great. Wonderful in fact.

I thought I had it narrowed down to the convergance board on back of the tube. I had someone watch the display while I gently wiggled it. They told it I was making it do the problem. So, I removed the board from the back of the tube and reseated all the conections, pressed it back on the tube and it seemed the problem stopped for a few days. Now its back.

I could just be wrong and the convergance board could not be the problem at all, I don't know much about these things....

Could anyone offer advise or a guess at what would cause the black level to blink brighter or darker randomly?

Thanks!