my enviro EF3-Bi is not running properly. now, upon startup and the first little while, there is a squeeling sound. last week, I noticed that my rope gasket inside the door was brittle, so I took it out, cleaned the area, put in cement and a new gasket. still squeels. does this sound like an air leak? the pellets don't seem to be burning as clean, more dirty, black gunk on the inside. before replacing the gasket, the fire would quite often go out in the middle of the night. any help would be appreciated.