Recently I noticed that there is a 1" gap where the original main duct (coming off the furnance/AC) connects to a new duct that we had installed a few years ago. It's on the top side so it was hard to see. The new stuff is about an 1" smaller than the old and the installer (who is no longer in the business....) didn't install a reducer. He just made a flap and put some tap on it and now tons of air blows out since it's only about 2' from the blower. The local hardware stores don't carry reducers like this. Does anyone know where I can have one made or the best way to seal an opening like this?