Check the gasket at the top of the door. I took my woodmaster door right off. Laid it down, cleaned the old gasket out. Installed a new gasket with some high temp silicone to hold it in the grove. Then I filled the whole face of the gasket with hightemp silicone , screeded it all off even with the edge of the door. Let it dry over night. Put the door back on. Works great.Never gets hard. You might have to adjust the door. Woodmaster, I heated the latch inside and bent it with a fork tube off a harley. Wood master told me to slam the handle against the frame of the door when it was loose one time. NOOOOOOOOOO WAAAAAAAY! It's probaly going to be tight anyway. It will get a little looser after a week. Emailed Woodmaster to tell them, they should make an adjustable door like my neighbors Wood Doctor , but guess the didn't want to hear some customer input. Never emailed me back. A Wood Doctor you can adjust in or out, left to right and I believe up and down. Nice set up. Only saying this because a good door seal is vital. How's those apples!