I have a HLT6176SX that is now out of warranty. I have both black and white spots on the screen. (not caused by dust)
I've replaced the DMD Board with no change, and now believe the DMD mirror is acctual bad, dead pixels, but can't find a Samsung Part #. The part number on the back of the chip finds Google results but only from UK suppliers. I can't believe Samsung doesn't have the part. Whether they'll give u thier part number is a different issue.