Hi All. The air control lever on my Osburn Stratford II high efficiency fireplace leaks cold air into the room when the fireplace is not burning. I did not install the outside air damper control valve since the run from outside to my fireplace was very short. Not enough room to install it. It looks to me that this could be fixed by installing a fireproof gasket(similar to the door gaskets) around the lever slot. Has anybody done anything like this? Or know of other units with a similar sliding lever that has a gasket? Thanks.