I was seeing more than the usual ash left over after a burn, and it failed to start more often. It still was running ok, but I had that nagging feeling. I have been doing my cleaning including the leaf blower, but my reassuring telltale whistle after cleaning was absent. Last evening while the stove was running I checked the firepot to see how things were going when something caught my eye. There was a clean spot about 3/4" long on the left edge of the firepot gasket. From time to time I check the gasket, but all you can see is a small edge that protrudes beyond the firepot rim. A closer look at the hard to see front with a small mirror seems to show another bad piece of gasket. I'm guessing these gaskets last a certain amount of burning slowly get brittle then suddenly let go as the air pressure from the exhaust pulls the weakened pieces out. I think mine is 4 years old, and is on 24X7. Quad doesn't list the size, and their cost is unreasonable. I think it's around $20. I found this gasket that looks like it might fit, and the price is right. http://heiligkuh.com/bbandp/product_info.php/cPath/22_25/products_id/30 Does anybody have the actual measurements? I am hoping all I need to do is disconnect the pull rod, igniter, move the thermocouple out of the way, then fight with the firepot bolts.