It could also be the internal power inverter, light source, or cable. Could also be bulging capacitors on the logic board that could be removed and new ones soldered on, or the logic board could be replaced. Can be very hard to diagnose, and the parts are usually quite expensive and often non-returnable if it turns out not to fix your problem.
I recently looked at the NEC PA241W, Asus PA246Q, and a few Dell models. Decided to go with the Asus PA246Q, only being $460. I highly recommend it, although haven't had an NEC PA241W to directly compare against. On paper, they look nearly identical.
1. The symptoms (a gradual dimming of the panel brightness) don't point at any of these other symptoms and the MTBF of the panel is like 10x less than discrete components anyway.
2. The art of finding a technician who knows what they're doing can be a problem. But once you find one they won't think it's hard to diagnose..
3. Factory components are often way overpriced and no one accepts a return where the package has been opened. Fair enough. But there are tons of generic components out there. As an example I recently repaired an LCD, LCD driver, and 9 diodes (lamps) on a transceiver. Factory price was a stunning $78.. Generics came in at $5.20.. I've nothing against quality generics.