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 InspectionHandlebar Installation
Apply a non-permanent locking agent to the threads of
the handlebar positioning bolts and tighten them.
Torque - Handlebar Positioning Bolts: 9.8 N·m (1.0 kgf·m,
87 in·lb)
Install the steering stem head with handlebars.
Install the washer [A] and steering stem head nut [B].
Tighten:
...
Operating Procedures
Clean the seat area carefully.
Coat the seat with machinist’s dye.
Fit a 45° cutter into the holder and slide it into the valve
guide.
Press down lightly on the handle and turn it right or left.
Grind the seating surface only until it is smooth.
NOTICE
Do not grind the seat too ...
Drive Chain
The drive chain slack and lubrication
must be checked each day before riding
the motorcycle and must be maintained
in accordance with the Periodic
Maintenance Chart for safety and to
prevent excessive wear. If the chain
becomes badly worn or maladjusted -
either too loose or too tight - the c ...