Optoma GT720 - Large Dark Spot (Pictures)

Alright, so I'm very new here, but I'm hoping someone can provide some help. I'm trying to fix a projector for some neighborhood kids. It's a long sob story, but basically their dad is very sick (cancer) and I'm just trying to take one thing off his plate. Anyway, when they first called me a few weeks ago the bulb was dead. Easy fix, I installed a new bulb and things seemed to be working great, however now just a few weeks later there is a large dark spot in the center of the image. Doing some reading here it sounded like it could be the light tunnel, but upon inspection that looks good. Any ideas on the cause and hopefully a fix?



PS: The spot is not green, that's the wall color. It's basically just faded. Also, that lighter blue spot on the right must just be my poor photography skills.
Edited by lpeters82 - 7/1/12 at 8:22pm

Still hoping for some help. Please note if this is the incorrect forum for such questions.

Thank you

Bump

I don't think it's the wheel. I had to take it off to get to the light tunnel and didn't see anything unusual. I also don't hear anything unusual when starting the projector. The only change with the new bulb would be an overall "hot smell". From what I've read this is common.