I have a Century Heating Whistler non EPA stove. This is my third year burning. Last year went really great. I moved my damper up into the flue pipe out of the connection collar at the stove where it originally was and i was able to close the damper the entire way after it got going and the fire would burn beautifully. This year when i get a fire going i leave the damper all the way open until the stove and fire get up to temp, just like i did last year. But when i close the damper the whole way the fire either pulses and wants to back puff out my intake holes, and when i crack the damper a fireball erupts and has shot flames out the intake holes. Or the fire just goes out and the smoke wants to roll back into the house out of the intake holes. So i have to leave the damper cracked a little more than i did before. I dont know what is different, im using wood from the same pile that i stopped using from in the spring. My methods are the same. I had everything apart a couple weeks ago to check it before i burned. I did replace all my windows recently from old drafty ones to new vinyl. But the porch where i have this stove is plenty drafty (old storm windows). Im just stumped. Im about ready to pull it all apart again and double check everything. Any ideas?