Mine was getting pretty bad after several years use. Used high-pressure air, low-pressure air, vacuum, tried brushes and all sorts of cleaning tools. no way! So, just gave up and got my screwdriver(phillips). Fan case opens on seam, four recessed screws on the back(be careful and don't drop). Made sure it was unplugged, then dusted it well, cleaned each blade with cloth and spray, used brush, wipes and air to clean entire case, screens, and everything I could get to. Carefully put it back together, and tested! Runs better, much less noise, and more air. Clean blades are really important. Make sure they are all good and clean, any dirty spots will make it out-of-balance.