Smooth sanding depends on a backing pad that remains flat, flexible, and firmly attached. Replace the pad if it is cracked, warped, hardened, or no longer holds the abrasive correctly. Check the sander spindle and mounting pieces before ordering, then match the pads size and speed rating to the full tool model. Shut off and disconnect the...Read more compressed-air supply, wait for all movement to stop, and wear eye protection. Make sure the pad runs true without wobbling before returning to normal use.