Replace the wheel rotation sensor if it is cracked, bent, or otherwise damaged.

Rear Wheel Rotation Sensor Installation
Wheel Rotation Sensor Air Gap InspectionExploded View
CL: Apply cable lubricant.
EO: Apply engine oil.
G: Apply grease.
HG: Apply high-temperature grease.
L: Apply a non-permanent locking agent.
M: Apply molybdenum disulfide grease.
R: Replacement Parts
S: Follow the specified tightening sequence.
Specifications
Special ...
Engine Installation
Apply molybdenum disulfide grease to the threads of the
adjusting collars [A].
Install the adjusting collars to crankcase backside until
end of the threads.
Install the adjusting collar [A] to the frame until end of the
threads.
Replace the engine mounting nuts with ne ...
Drive Chain Lubrication Condition Inspection
If a special lubricant is not available, a heavy oil such as
SAE 90 is preferred to a lighter oil because it will stay on
the chain longer and provide better lubrication.
If the chain appears especially dirty, clean it before lubrication.
NOTICE
The O-rings between the side plates seal ...