Dell monitor 2209WAF problem

[rlovison]

I've had this monitor for about 6 years and use it exclusively for photography as it has an ips panel and the viewing angles are fantastic. It just started acting up where at different times of the day it will suddenly dim in brightness and then within minutes pop back up to the correct brightness. Anyone have this happen to an LCD computer monitor? I had it apart and all the electrolytic capacitors looked ok. There are only three boards... the power supply/main board, inverter board and a usb board. I guess I'm going to need to wait until it fails further before I can do any voltage tests.