If its cold out, that could very well be the problem. Try moving the shaft to see if the flap is loose or not. Most of them stick in the closed position (heat going out the pipe). If it is loose, turn it opposite what it is now and wire it in that position. You may have to clamp some vise grips to it and then wire it in the open position.
If its stuck, start spraying the shaft now and everyday for a week or so, then keep working the shaft a little at a time. It should come loose after a while. The side opposite of the spring, has a small cap (freeze plug type) over the shaft end, you can drill a small 1/8" hole in the cap so you can get your oil into the shaft area. Joe
