This stove is driving me crazy. It will start up with a beautiful flame run for 40 minutes and shut down. I've done everything I know to do or can find to do and still the same. The exhaust blower is working, the auger is working, the photo eye is clean, I have cleaned inside and out. the fan is working as well but when I change it to 2nd or 3rd speed the fan does not pick up. It stays on 1st speed. This is my main source of heat and it has been getting down to 12 at night. Please any help would be greatly appreciated.