I've had my Whitfield Pellet (Profile 20)stove for 3 years. Worked OK until last week when the temp dropped in the double digits. The top of the flame is orange and red and lazy. Fuel is often left unburnt and the doors are covered with black (not gray) soot within a couple of hours. I have cleaned everything that you can imagine on that stove. I have spent over $400 on technicians and I still cannot use it. The shop I bought it from won't aknowledge I have a problem. I know its not the fuel because I exchaned a bag with a friend who owns a Harmon Pellet stove and the fuel is fine. Can anybody share some helpful hints.