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 InspectionPremuffler Chamber Installation
Replace the premuffler chamber gasket [A] with a new
one.
Install the premuffler chamber gasket to the premuffler
chamber [B] until it is bottomed so that the chamfer side
faces exhaust pipe [C].
Install the exhaust pipe clamp [D] as shown in the figure.
Insert the projection [E] into ...
Drive Chain Slack Adjustment
Remove the cotter pin [A], and loosen the rear axle nut
[B].
Loosen the both chain adjuster locknuts [C].
If the chain is too loose, turn out the left and right chain
adjusters [D] evenly.
If the chain is too tight, turn in the left and right chain
adjusters evenly, and kick the wheel f ...
Armature Inspection
Using the × 1 Ω hand tester range, measure the resistance
between any two commutator segments [A].
Special Tool - Hand Tester: 57001-1394
If there is a high resistance or no reading (∞) between any
two segments, a winding is open and the starter motor
must be replaced.
...