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 InspectionECU Removal
NOTICE
Never drop the ECU especially on a hard surface.
Such a shock to the ECU can damage it.
Remove the upper air cleaner housing (see Air Cleaner
Element Replacement in the Periodic Maintenance chapter).
Lift up the ECU [A] with rubber protector [B] to disconnect
the connectors [C]. ...
Periodic Maintenance Chart
K : Should be serviced by an authorized Kawasaki dealer.
* : For higher odometer readings, repeat at the frequency interval established
here.
# : Service more frequently when operating in severe conditions: dusty, wet,
muddy,
high speed, or frequent starting/stopping.
(e): Emission Rel ...
Spark Plugs
The standard spark plug is shown in
the table. The spark plugs should be
replaced in accordance with the Periodic
Maintenance Chart.
Spark plug removal should be done
only by a competent mechanic following
the instructions in the Service Manual.
Spark Plug
A. Plug Gap ...