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 InspectionCheck 3-6: Neutral Indicator Light (LED) Inspection
Connect the leads in the same circuit as Check 3-2.
Connect the terminal [8] to the battery (–) terminal.
Check that the neutral indicator light (LED) [A] goes on.
If the indicator light does not go on, replace the meter unit.
...
Starter Clutch Removal
Remove:
Torque Limiter (see Torque Limiter Removal)
Transmission Assy (see Transmission Assy Removal)
Starter Clutch Shaft Holder Bolt [A]
Starter Clutch Shaft Bolt [B]
Starter Clutch Shaft Holder [C]
Remove the starter clutch shaft [A] using a suitable M8
bolt [B].
Take ...
IC Igniter Inspection
The IC igniter is built in the ECU [A].
Refer to the following items.
Interlock Operation Inspection (see Interlock Operation
Inspection)
Ignition System Troubleshooting (see Ignition System
section)
ECU Power Supply Inspection (see ECU Power Supply
Inspection in the Fuel System (D ...