Since you tv is over five years old, it may be time to buy a new bulb.
they do dim over time...
I purchased a DLP Mitsubishi model WD-52525 [$3799] in '04 from Sears along with a 5yr protection plan [$699]. When I compare my pictures brightness against a new DLP Mitsubishi model WD-60735 its like night and day. My set looks dim even at its brightest setting. I cannot find any specs in my manual for lumen output.
My question is are the newer sets simply brighter? Or, should I be calling Sears to use my repair policy.
Thanks in advance for any input.