Replace it if necessary.

Inner Tube Inspection
Spring Tension InspectionSpark Plug Condition Inspection
Remove the spark plugs (see Spark Plug Replacement in
the Periodic Maintenance chapter).
Visually inspect the spark plugs.
If the spark plug center electrode [A] and/or side electrode
[B] are corroded or damaged, or if the insulator [C]
is cracked, replace the plug.
If the spark plug is ...
Cylinder Head Cover Removal
Remove:
Air Suction Valves (see Air Suction Valve Removal)
Throttle Body Assy (see Throttle Body Assy Removal in
the Fuel System (DFI) chapter)
Stick Coils (see Stick Coil Removal in the Electrical System
chapter)
Remove the clamps [A].
Turn up the front side of the heat insulation ...
Rear Brake Pad Installation
Check that the pad spring is in place on the caliper.
Push the caliper piston in as far as it will go.
Install the piston side pad [A] first, and then another pad.
Fit the brake pad end into the recess [B] of the caliper
holder.
Install the pad pin and the plug.
Tighten:
Torque - ...