I have had a Hearthstone Heritage 8021 since 2016. I don't think the primary air control ever worked. It moves from left to right and back freely but has no noticeable impact on the air flow in the stove. We were never in the house with the stove long enough for it to bother us (experienced with wood burning stoves) and we just put up with the lack of control. Essentially we used the door to control the air. Now we are here for longer stretches in the winter and the problem is much more of an annoyance. The air control lever moves freely from left to right. I can see it is attached to a semicircular plate. I cannot see or hear any other movement. I am thinking either something is clogged or the lever and semicircular plate are disengaged from something. Does anyone have any experience with this issue?