With the advice I've gotten here, I've finally managed to get my old Sierra Hearthstove to work almost properly. Even got into a proper overnight burn last week. However, it seems that the air is not circulating through the stove as it should. When I get ready to load up for the overnight, I rake the live coals from the back of the stove to the front, to be near the vents, and then stack the fresh splits up against the back of the stove, shut the door, and wait until I see them flaming and then shut the vents down about 75% and go to bed. In the morning, I still have a pile of red coals at the front of the stove, but a large pile of unburnt coals at the back. Large enough that I can scoop them out and use them in the barbecue... just light 'em again. Tried leaving the vents open 100%- no change. This can't be good... those coals should be burning, not cooling!