Overheating BenQ HT1075

Hi All! I have a BenQ HT1075 with about 600 hours on the lamp. The fan is turning fine and moving air and it's mounted a bit over 12 inches from the ceiling and it now is overheating every time I use it after about 30-45 minutes. I know there are a lot of BenQ people on this sub. Any advice or thoughts on what might cause this?