Disposal runs but water drains very slowly from the sink; internal LED flashes five times.

Safety first: Turn off power to the disposal and do not operate it while dismantling plumbing.

• Check for simple sink blockage: Run water with the disposal off. If water stands in the sink, the blockage is downstream of the grinding chamber.
• Remove and clean the discharge elbow: Place a bowl under the McAlpine discharge elbow. Loosen the compression nuts and remove the elbow. Clear any compacted food waste and rinse thoroughly.
• Clean the McAlpine trap: If a McAlpine P-trap or bottle trap is fitted, remove it and clear any sludge or obstructions. Inspect the trap seals and replace worn washers.
• Reassemble and test: Refit the elbow and trap, ensuring all compression nuts are hand-tight plus a small additional turn. Restore power and run water while operating the disposal briefly to confirm free flow.