Remove the under cover.
Using the hexagon wrench, turn the tensioner (A) counterclockwise and loosen. Then remove the drive belt (B).
Install in the reverse order of removal.
Visually check the belt for excessive wear, frayed cords etc.
If any defect has been found, replace the drive belt.
Cracks on the rib side of a belt are considered acceptable. If the belt has chunks missing from the ribs, it should be replaced.