Ok, so my air handler started making a noise the other day. I shut it off, then wiggled the fan a little. When I turned it back on, it was fine for a few hours. When the noise came back, I investigated a little further to find the small bolt that tightens the fan to the shaft loose, and tightened it. It seems the fan was rubbing against the side. Now that that bolt is tight, the fan makes no noise like normal, until it shuts off. The last couple rotations of the fan seem to rub on the side. I tried to loosen, reposition and retighten the fan, with unsatisfactory results. It seems there is extremely little room to slide the fan along it's shaft. Anyone have any suggestions? The unit is only a few years old, installed back in 2009.