Sony Trinitron tube shutting off? PVM-2530

Hi,

I've got a Sony Trinitron, PVM-2530, from the late 80's (one of the big 'cube monitors') that looks great. However, it has a problem. In fact, I've owned THREE, with the same problem.

Every so often, the screen will go blank. It makes a little 'psheew' sound, and the image disappears. It is as though the tube is going dead. Nothing will restore it, save turning the monitor off, and then back on again. And even then, it will often turn on for a second, then immediately shut off. The rest of the TV continues to work, audio, input switching, etc.

It seems worse when its cold, and seems to happen less when its warm. Sometimes the TV will go for days without doing it, other times it will do it every few minutes, making it unwatchable.

Two that I owned before this one (I got the three together, surplus), got so bad that they became useless. This last one is marginal... I can get through a whole movie about half the time.

Any insight? Any common part failures I should look into? Any idea on where I could get a service manual?

Thanks!
Sam