We have an older Auburn St. Croix corn/pellet stove that we bought used off of a friend. We love it EXCEPT, since last year, when we run the stove on the lowest setting, before too long the exhaust fan starts making this rattly/janky noise and then after a bit the fan will stop entirely, and smoke enters our house. My husband took the fan entirely out and cleaned it very well, and for the remainder of that day it ran perfectly on a low setting. But today, the second day of use, it has started to do the same noise again that precedes it's quitting. Can anyone tell me why it is doing this and what we should do about it? Thank you!!