If there are notches worn into the splines, replace the sub clutch hub. Also, replace the steel plates if their teeth are damaged.

Clutch Housing Finger Inspection
Damper Cam InspectionStarter Relay Inspection
Remove the front seat (see Front Seat Removal in the
Frame chapter).
Remove the battery negative (–) cable from the battery
negative (–) terminal (see Battery Removal).
Take the starter relay [A] off the rear fender.
Remove the cover [B].
Remove:
Starter Motor Cable [A] ...
Oil Pump Installation
Install the outer rotor [A] into the crankcase.
Assemble:
Oil (Water) Pump Shaft [B]
Pin [C]
Inner Rotor [D]
To prevent dropping, apply grease to the pin.
Install the inner rotor assembly into the crankcase.
Fit the slot [E] onto the projection [F].
Replace the O-ring [A ...
Rear Wheel Installation
Apply high-temperature grease to the grease seal lips.
Fit the collars on the both sides of the hub.
Left Side Collar [A]
Right Side Collar [B] (with Flange)
Engage the drive chain with the rear sprocket.
Install the caliper bracket [A] onto the stopper [B] of the
swingarm.
...