Yamaha Clavinova CLP-820 Owner's Manual page 54

10
D
?
Set the adjuster.
For stability, an adjuster is provided on the bottom of the
pedal box (D). Rotate the adjuster until it comes in firm contact
with the floor surface. The adjuster ensures stable pedal operation
and facilitates pedal effect control. If the adjuster is not in firm
contact with the floor surface, distorted sound may result.
54
CLP-880/860/840/820/820S