Howdy Folks, Just bought a house with a Blaze King BT-504 early 80's model in it. Cleaned the chimney with a brush and cleaned the ashes out before starting it. It seems to be running out of combustion air while burning and the fire will actually go out until you open the door up and let more air in. I pulled the back cover off of the thermostat revealing the air damper. At a setting of 5 the damper was closed and opened very little at 6. I pulled the stat off completely and took it outside as I had noticed it had a bimetallic coil in it controlling the damper. As it cooled off, leaving it at 5 the damper would open more. It cooled completely down allowing the damper to start opening at 2. So the stat seems to be working properly. I was wondering if a leaking door gasket could be causing to pull air past the door and causing more heat that would close the damper off? I have seen leaking gaskets cause problems on boilers and stuff I work on at my job. Thanks!