Our 4 year old Lopi 1750i flue damper won't close. Last season, it was really loud when opening and closing, kind of sticky and difficult to use. I started just not using it, leaving it closed. I rarely load when it's hot, so smoke coming into the house when I opened the door was not a concern. Today, we had a new stove installed downstairs and the Lopi and chimneys swept. The sweep opened the damper. I loaded and started it after he left, and now I cannot get the damper to close. So, now what do I do? I profess that I really don't know what the damper does and what happens if I burn with it open.