I am new to smokers. I bought a 40" MES last week. While precisely following the instruction book for preseasoning, the seal on the top edge of the glass door loosened and scorched the metal above the glass panel. I exchanged it at Bass Pro for a new one not knowing whether the first model had a defect or the preseasoning instructions were not clear. The instruction book says to close the air damper while cooking to retain moisture (except when cooking jerky or fish). The salesman says that he always opens the damper once the it reaches the desired temp. I don't know what brand smoker he has. Please let me know your thoughts, suggestions and experience with MES air dampers. This forum is a great source of information, recipes and encouragement. Thanks for sharing your exeriences.