NeXT monitor problems.

Hello, My NeXT mono monitor (N4000A) quit displaying properly. Symptoms were: 1) Over last 6 mo. or so, on start-up (this is only about 2 start-ups, machine running continuously in between), the middle 30% or so of the display was compressed into a single (bright) scan line. Top and bottom 30% were stretched, so the whole screen was continuous. This problem cleared after running for 1-2 minutes. 2) 4 weeks ago, noticed that (even after the start-up problem) what should have been a uniform grey background looked like it had small light and dark horizontal flecks in it, appearing and disappearing at something like the screen refresh rate. Made the background look grainy and sort of seething. 3) (After I was gone for 3 weeks on travel), monitor now flashes on and off on about a 1 Hz cycle time. A distorted and shrunk version of what should be showing is visible near the center of the monitor during the "on" times. There is a bright horizontal scan line near the middle of the image, when you can see it. 4) On start-up, nothing shows for at least 2 minutes. After around 2 minutes (as I was powering off), image (as in 3) above) started to appear. Have not repeated experiment to see whether it goes back to the 1-Hz cycle or not. Monitor has been running near continuously since I got it, in '96. Is this a known/easily fixable failure mode? Anyone have experience with this? I need the machine running and my record with repairing computers is dismal so I'm looking for (and think I have located) another monitor, but at some point I intend to take a crack at fixing this one. Replies to list if you please, in case this *is* a common problem - I'll catch up as fast as I can. -- - Mark 210-522-6025, page 888-733-0967