I have the same TV, which I bought about two years ago. I also noticed that my screen seems to be getting darker and I also have patches of yellow. I called in the extended warrenty I bought (thank god!) only to find out that the light engine is going on it. The light engine for this unit runs about $2,000. This is more than I spent on the TV but the warranty is covering it. I will let you know if this fixes the problem.