I have a Regency Hampton GC60 that I purchased about 2 years ago. After running for less than a day the glass starts to get dirty on the right side and top right side only. I have to clean it every couple of days or it takes a long time to clean after a week. I tried raising the combustion trim and lowering the fuel trim and that seemed to help a little. I burn engergex pellets. Anyone have any suggestions?