If a master cylinder or piston shows any damage, replace them.

If a cup is worn, damaged softened (rotted), or swollen, the piston assembly should be replaced to renew the cups.
If fluid leakage is noted at the brake lever, the piston assembly should be replaced to renew the cups.
If they are damaged, replace them.
If the springs are damaged, replace them.
If the relief port becomes plugged, the brake pads will drag on the disc. Blow the ports clean with compressed air.
Front Master Cylinder [I] Rear Master Cylinder [J]

Rear Master Cylinder Installation
Brake DiscThermostat Installation
Replace the O-rings [A] with new ones, and apply grease
to them.
Assemble:
O-rings
Thermostat Housing [B]
Thermostat [C]
Thermostat Cap [D]
Install the thermostat [A] in the housing so that the air
bleeder hole [B] is on top.
Tighten:
Torque - Thermostat Cap Bolts: 5.9 N ...
Rebound Damping Force Adjustment
The rebound damping force adjuster
is located at the upper end of the rear
shock absorber.
A. Rebound Damping Force Adjuster
B. To increase damping force
C. To decrease damping force
Using a screwdriver turn the rebound
damping force adjuster clockwise
to increase rebound damping or ...
ESD Actuator Resistance Inspection
Turn the ignition switch to OFF.
Remove the electronic steering damper unit (see Steering
Damper Removal in the Steering chapter).
Connect a digitalmeter to the ESD actuator connector [A].
Measure the ESD actuator resistance.
ESD Actuator Resistance
Connections: BK lead [1] ← ...