Inspect the belt for cracks or damage. If the belt is cracked or damaged, replace it.
Check that the position of the auto-tensioner indicator (A) is within the standard range (B) as shown. If it is out of the standard range, replace the drive belt.

Brake Assist System
■Brake Assist System
Designed to assist the driver by generating greater braking force when you
depress
the brake pedal hard during emergency braking.
■ Brake assist system operatio ...
Rocker Arm Assembly Removal
Remove the cylinder head cover.
Loosen the rocker arm adjusting screws (A).
Unscrew the rocker shaft mounting bolts two turns at a time in the
sequence shown.
...
Installation
Hold the gearbox housing using a C-clamp (A) and wooden blocks (B) to a
workbench as shown. Do not clamp the cylinder part of the gearbox housing in
a vise.
...