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 InspectionAir Suction System Damage Inspection
Separate the air switching valve hose [A] from the lower
air cleaner housing [B] (see Air Cleaner Housing Removal
in the Fuel System (DFI) chapter).
Connect the following parts temporarily.
Fuel Pump Lead Connector [A]
Extension Tube [B]
Air Cleaner Housing (see Air Cleaner Hou ...
Precautions
1) No need of topping-up
No topping-up is necessary in this battery until it ends its life under
normal use. Forcibly prying
off the seal cap to add water is very dangerous. Never do that.
2) Refreshing charge.
Give refresh charge for 5 to 10 hours with charge current shown in the text
(see ...
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.
...