Replacing gaskets and removed the damper. When I close the damper the right side drops down and won't seal. The left side, the side where the lever is the damper slides behind a flat tab that's bolted to the stove which holds it in place. The right side has a metal tab that is a 90* tab that just sits over the damper shaft. Antone have a suggestion what's wrong? Is the right side tab supposed to go around the damper shaft?