ViewSonic P220f

It's pretty likely one is not even available unless you're an authorized service center.

What's wrong with the monitor? These have a few specific problems that happen with almost every one of that model.

Is one of those problems that it eats LM2412 video amplifiers? I repaired one by replacingtha and a couple of nearby transistors and some arc protection diodes. It seemed to be working fine, but it lasted only a few hours before the smoke came out of the new 2412. All power and other voltages were nominal, and essentially identical to those on another, good P220f.

Isaac

Replace the 4N35 optoisolator in the power supply, these almost always fail but you'll be chasing your tail forever trying to track it down without knowing that as it's intermittent. On one I had, I had to resort to soldering in some wires to an old benchtop DMM monitoring the voltage to the vertical output IC and use it like that for several weeks before I caught it creeping up. I hit parts with freeze spray until I got to the opto and the voltage dropped right back down the instant I cooled that part. I've fixed at least half a dozen 17, 19 and 22" models with the same basic chassis by replacing that stupid opto. Usually it takes out the vertical output IC but I've seen other things blow up.