I've had this reliant since 1987 with no problems for 25 years. This year, noticed the griddle and corners of the stove smoking when I put it in long burn. changed the griddle metal fiber gasket, but still smokes. Here's the sequence: 1. when it's burning fully open, it works fine. 2. when I close the damper for a long burn with the fire hot, it immediately smokes from the griddle gasket and 2 of the top corner seams. 3. It continues to smoke until I lower the temperature until the temperature gauge is near the "+" mark on the stove. the smoke stops, but the temp. goes way down. when I try to increase the temp., the smoking starts again. I'm not sure if something internally is partially blocking the exit to the chimney as the air increases, or what? any advice would be appreciated. thanks, George H.