If any is worn down to the service limit, replace the brush assy.
Starter Motor Brush Length [B] Standard: 12.05 mm (0.4744 in.) Service Limit: 6.55 mm (0.258 in.)

Starter Motor Assembly
Commutator Cleaning and InspectionDFI System Troubleshooting Guide
NOTE
This is not an exhaustive list, giving every possible cause for each
problem listed. It is meant
simply as a rough guide to assist the troubleshooting for some of the more
common difficulties in
DFI system.
The ECU may be involved in the DFI electrical and ignition system
tro ...
Clutch Plate, Wear, Damage Inspection
Visually inspect the friction and steel plates for signs of
seizure, overheating (discoloration), or uneven wear.
Measure the thickness of each friction plate [A] at several
points.
If any plates show signs of damage, or if they have worn
past the service limit, replace them with new on ...
Rider’s Seat Removal
Remove the bolts and seat cover.
A. Bolts
B. Seat Cover
Remove the mounting bolts and pull
off the seat upward.
A. Mounting Bolts
B. Rider’s Seat ...