pulled my auger out of the harman Accentra insert this morning trying to get to the bottom of the squealing during pellet feed issue that others have reported. Auger looks rather good except at the burn pot end where there is a thin layer of black buildup. Can I hit this with a wire wheel to take it off or would creating fine scratches be a bad thing? Have tried vinegar and 200 proof ethyl alcohol which did not do anything. Just want to ensure I clean as best as possible before I reassemble.