You may also want to check where the cast arbor assembly pivots. There is a fairly large pin where it pivots that may be gummed up or rusted. Removing the pin is a fairly simple task. First remove the throat plate, remove the blade, lower the arbor and you should see a set screw above where the assembly rotates. Loosen the set screw and pull the pin, you may have to tilt the assembly to pull the pin, I can't remember. Another thing to check is the gear lashes, how the gears mate with eachother. There is a way to adjust the lash, the bushing inside is ecentric. An Owners Manual describes the procedure with pictures.