We inherited a Whitfield Insert when we purchased our house and it's a bit cranky from time to time. Several years, I had a professional come and clean it, but I've recently taken to doing it myself (after watching what he did). Currently, I'm having some problems. I was getting a lot of black soot on the glass. So, after my annual cleaning didn't help, I replaced the door and ash compartment door gaskets. This helped, but I'm still having some problems 1. Can't open the damper at all or the fire gets too hot (combustion trim is set at factory settings). 2. Even with heat set at 1, it gets pretty hot. Above 3, pellets just build up in the UltraGrate and eventually overflow (I have the auger timing trim set to minimum). We live at 6800' elevation. I don't know if this has consequences, but it would seem that the damper might need to be more open, not less. When I did open heat up to 4, the soot reappeared and the Ultragrate filled up. However, if I tried opening the damper, live pellet coals flew all around. Any ideas? BTW, I don't think that I did a very good job on the door gasket. I can see the fire from one of the door corners (just one place).