How difficult is it to change the burn pot on a PF100? I don't know if I have a hard carbon build up on the right side ramp of the burn pot going down to the auger or a bubble. I'll have to get a mirror and flashlight in there to see. Furnace is under warrantee but my dealer is out of business. I may have an avenue to get a burn pot under warrantee, but I'd have to put it in myself.