I have a one year old Buck model 81 and the left side of the window glass was constantly getting dirty. My wood is dry and I burn fairly hot fires. Took me awhile to solve this issue. Finally figured out that the air wash baffle was practically touching the glass on the left side of the door because the door fits tighter to the stove on that side. I have seen people posting of this same issue in the past but can no longer post on that thread. The solution that worked for me was to file back the baffle until the gap from the baffle to the glass was the same on the left side as the right. I'm guessing about 1/16 inch is what I filed off. Works great now with no discoloration