If they appear damaged or deteriorated, replace them.

Balancer Adjustment
Torque LimiterCommutator Cleaning and Inspection
Clean the metallic debris off the between commutator
segments [A].
NOTE
Do not use emery or sand paper on the commutator.
Check the commutator for damage or abnormal wear.
Replace the starter motor with a new one if there is any
damage or wear.
Visually inspect the commutato ...
Wiring Diagram (Other than US, CA and CAL without KIBS Models)
ZX1000JC
ZX1000JD
...
Diode Circuit Inspection
Remove the relay box (see Relay Box Removal).
Check conductivity of the following pairs of terminals (see
Relay Box Internal Circuit in this section).
Diode Circuit Inspection
The resistance should be low in one direction and more
than 10 times as much in the other direction. If any dio ...