A disposal that hums, buzzes or does nothing

Before anything: the switch off

Nothing goes into that opening — not a hand, not a spoon — until the unit cannot start. Switch it off at the wall, and if there is a cupboard breaker or a plug under the sink, use that too. Disposals start the instant they are powered, and they do not care what is in them.

It hums but does not turn

The motor is getting power and cannot rotate. Something is wedged between the impeller and the grind ring — commonly a cherry stone, a bit of bone, a bottle cap, or a small spoon.

Underneath the unit, in the centre, there is a hex socket. The small L-shaped key that came with the disposal fits it, and a quarter-inch hex key works just as well. Turn it back and forth a few times; you will feel the jam let go. Then look into the opening with a torch and get whatever it was out with pliers, not fingers.

Once it is free, press the small red reset button on the underside, restore power and run it with plenty of cold water.

It does nothing at all

Silence is an electrical story, and it has three likely chapters.

The reset has tripped. Red button on the underside. Press it firmly until it clicks. This is the first thing to try and it is free.

The breaker has tripped. Check the panel.

The switch or the outlet is dead. If the reset is in, the breaker is on, and there is still nothing, the fault is upstream of the disposal. That is electrical work, and it is where I stop and you call an electrician. A disposal that does not run because of a dead switch is not a disposal problem, and replacing the unit will not fix it.

It rattles

Usually something loose in the chamber, and usually a teaspoon. Power off, torch, pliers.

If the rattle is metallic and constant rather than intermittent, the impellers may have come loose, and that is the end of that unit.

It leaks

Where it leaks from decides whether this is a repair or a replacement.

• From the top, where it meets the sink. The mounting assembly or the sink flange gasket. Repairable.
• From the side, where the dishwasher hose or the drain elbow connects. Usually a gasket or a loose clamp. Repairable, often very quickly.
• From the bottom of the body itself. The housing has corroded through. The unit is finished; no gasket will fix it.

What actually kills them

Not the things people worry about. Coffee grounds and eggshells are not the problem, and citrus peel does not clean anything. The real offenders are fibrous waste that wraps the impellers — celery, artichoke leaves, corn husks — starchy quantities that turn to paste, like a whole pan of rice or mashed potato, and fat poured down warm, which sets further along the pipe where it is somebody else's problem until it is yours.

Plenty of cold water while it runs, and for a few seconds after it has finished, does more for a disposal's life than anything you can put down it.

What this costs if you would rather not

A straight replacement of a failed unit — old one out, new mount, new unit, drain elbow reconnected and every joint checked under running water — is an hour to an hour and a half. If the fault turns out to be the switch or the outlet, I will say so and not charge you for a disposal you did not need.