Just an update for anyone sharing the same problem, I took the projector apart as detailed in a previous post in 2011, used my air compressor to thorougly clean all the fans and circuit boards and removed the color wheel. Using denatured alcohol and a q-tip I cleaned both sides of the wheel. You don't have to remove the color wheel to clean it but I chose to do it to really visualize the result. There were quite a few very small dust particles on the wheel. Additionally, there is a metal box that houses a mirror that sits below the wheel that had several dust particles on it. To access this little box, I flattened out a q-tip and cleaned that as well. Used my compressor one more time and re-assembled the projector. All issues of blotchiness and yellowish tint to white areas on the screen are gone. There was also some ever so slight flickering that I didn't mention in my original post that has resolved as well. Did not have to sync the color wheel as of yet. So, although I don't like having to tear apart my projector, it was well worth it!!! We will see how long it lasts. For the record, I called Optoma in the past regarding this issue and tech support did not hesitate to say the main board needed to be replaced and that it would cost about $400....don't think so! Apparently, at least with mine, dust build up is a problem. Oh well, still a great projector and worth the cleaning once a year or so to maintain that great picture!