Jikapp, sounds like your rotor air ump may be getting worn down. TSC used to carry the replacement kit for it last time I was looking they didnt have one. You have to take the back cover off (the plastic that holds the filters) then remove the back cover. Oval aluminum about six-eight screws. You will see a black round disc with four fins in it. Pull it off of the shaft. loosen the screws holding the backcover to the motor. (You will need to set your clearance for the new rotor.) Install new rotor just as the reverse of removing the old one. Use a .005 feeler guage and roll it just along the top of the rotor and push the aluminum housing down to hold the feeler guage . Tighten surounding screws and re assemble.