I own a Harman Invincible Pellet Stove (an Insert). The distribution blower just doesn't move a much air as it used to. When I turn up the stove temp dial all the way, it only blows with half the force it used to when maxed out. I don't know if this is a problem with the switch, the blower, or something else. Has anyone ever experienced this problem and if so what was the reoslution? Thanks!