Question: I have a model 2190 Vermont Castings Encore and it is about 4 years old. The flue damper seems not to operate properly in that the damper will fall open in the night from catalytic mode to fireplace mode with a loud thud.I am not sure which part is at fault. The new encore has an adjustment screw mine does not. I am debating on replacing the torsion bar on the damper. Would this make sense or are there any other suggestions. Answer: When this usually happens, it's because the damper is not being closed fully. It is quite easy to close the damper and think it is locked..when it is not. You have to push very hard after ther damper closes and then it will snap into a locked position. Assuming you are already doing that, then perhaps a part has excess wear. But, in my experience, it is almost impossible for the damper to fall open from the completely locked position.