I recently bought an HT300+ second hand from a dealer. I was told by them that the bulb had been replaced and the counter on the menu shows that it has 160 hours (on the clock). Unfortunately my 3 month guarantee is up. I have noticed that the image brightens and darkens randomly very slightly. Sometimes it can be desribed as a flicker, other times the dimming lasts 15 seconds or more. It's beginning to irritate me as I am now more aware of it than the movie that I am watching. If I put up a blank (blue) screen I can see this clearly. Any suggestions as to what this might be? Is this a bulb failure, or something more sinister with the projector? Any help would be much appreciated.