Damper will not close completely. It keeps hanging on right end against the metal up inside there. I have tried to reach up in there with small grinder as best I could, but does not solve the problem. I cannot tell if the damper itself is warped and needs replacing or whether the problem is a warping alongside where the damper opens. I am contemplating whether to pull out the insert (dreaded weight) and see if I can better access the problem from topside. Would anyone out there have a clue or ever experienced such a thing? Thanks for any insight