The advance lever translates the motion thru a clutch and gear set system. The best way to fix this is to get the wind assembly and replace it Vs trying to fix the clutch or gears.
You'll need to take the lens mount bezel cover off (four screws) then take the top cover off (six screws). spin off the lever cap screw and the lever parts and the rewind crank (left hand screw). Slowly lift the cover you'll still have a wire attached to the Hot Shoe. locate the four screws that hold the winder assembly. Carefully lift the assembly and replace with the new one.