I am new to pellet burning. I have a Pleasant Hearth 35k btu stove. I bought some Crabbe softwood pellets that started out burning ok, Brown soot, and a little clinker, but not too bad. Now after burning 600 or so pounds I can’t get them to burn well even with the air cranked wide open. Quite a bit of soot, orange flame, basically hell. Don’t know what to do. Venting is up and out Selkirk L vent w/OAK Is It The stove, the pellets, or the operator.