Secure pad mounting is essential for safe, smooth sanding. Damage to the retaining nut can allow the backing pad to loosen, vibrate, or separate from the spindle. Check the nut threads and pad center before ordering a replacement. Match the part to the full sander model and parts diagram. Shut off and disconnect the compressed-air supply,...Read more wait for the tool to stop fully, and wear eye protection. Never use a cracked nut or force a part with the wrong thread onto the spindle.