So I have burned in this stove for some years, it is a 1978 VC Resolute with glass in doors. LOVE it! At the end of last winter I was having some fires when it was low 60s and high 50s and each time about 45 minutes after getting the fire going, hot about 600 degrees I damped it down( on this wood stove it is either open or closed) had the rear "thermostat" at straight up position but it is closed until it starts to close down, and PUFF with a noise like a very small explosion in the stove. Smoke did come out the hinge side of the door before it did its "explosion" by a minute or so it just oozed out and then POOF with a lot of smoke and it did it a second time. I opened up the damper let it burn about 5 min and closed it and shortly afterward it POOFED again, opened up the damper and let it get really hot then again closed it and NO MORE POOFS. I have read other posts and they all talk about not damping down completely but this stove is either closed or open, no in between. Every once in a while, the damper crashes open so need to have that fixed but what in hell is going on. I used wood that was seasoned for last year so well seasoned now of course. I did not use small kindling, use firestarter and newspaper and then smaller quarters of good hard wood and some cedar. I will be kicked out of the woodstove use if this continues so help is needed. By the way, I thought it was because we needed the chimney sweep so he came today before this fire and it still did it exactly as it did previously so it was not a stopped up pipe.