My PDV 25 is squeaking every time the lower auger turns. I have greased the bearing and it still squeaks. I removed the auger shaft and found carbon build up near the opening in the fire box. I cleaned that all out and it was very quiet again but only for one day. There is no way that all that carbon I cleaned out is there again. Any suggestions out there? It seems that the auger rides in the tube metal on metal, to me this is a bad design.