I had a Nokia 445xpro 21" as well. I've since replace it with a 23" Apple Cinema display and handed it down to a graduate student. It's still humming along, five years later, although it's noticably dimmed. Even when it was new, it had some power issues. If you cranked up the contrast to the level that it would start looking almost as sweet as an LCD, then the monitor would noticably react when a big part of the screen went from black to white (e.g., when web surfing). I figure they didn't give it a big enough power supply or something.

Honestly, it's really hard to justify repairing an old CRT when new CRTs (much less LCDs) have come down so much in price. At NewEgg, 21" CRTs range from $364 to $469. The top-of-the-line 22" NEC/Mitsubishi is still only $645. At that point, you're getting into the starting price range of 20" LCDs with 1600x1200 pixels. Go ahead, you know you want one.