Disposal runs but makes a loud metallic grinding or rattling noise; LED flashes eight times.

Safety first: Switch off power at the wall and breaker. Never reach into the chamber with your hand.

• Visual inspection: Shine a torch into the sink opening. Look for foreign objects such as cutlery, bottle caps, or screws.
• Remove debris: Use long-nose pliers or tongs to remove any visible objects. Rotate the impeller plate manually (using a wooden spoon from above or the hex key from below) to expose hidden items.
• Check impeller arms: Ensure the McAlpine impeller arms are secure and pivot freely. If an arm is loose or broken, the grinding plate assembly should be replaced.
• Test operation: Restore power, run water, and briefly operate the unit. If the metallic noise persists, internal components may be damaged.

Persistent loud metallic noises after debris removal usually indicate a cracked grinding ring or damaged impeller plate, requiring replacement of the grinding assembly or entire unit.