Question one — does it have power? (Complete silence when you switch it on.)
No sound at all means nothing is reaching the motor. This is electrical, not mechanical, and it's the cheapest possible outcome.
Check in this order: the reset button on the underside of the unit — a small button, usually red, that trips when the motor overloads. Let it cool for a few minutes, then press firmly until it clicks and stays in. Then the breaker. Then the wall switch, which does occasionally fail.
If the reset trips again immediately, stop. Something is jamming it or the motor is failing, and repeated resetting addresses neither.
Where the fault is: the unit's overload, the circuit, the switch, or — least often — the motor itself.
Question two — does it turn? (It hums but nothing happens.)
A hum means power is arriving and something is preventing rotation. That's a jam, and it's the second free fix.
Isolate the power at the breaker first. Then use the hex wrench that shipped with the unit in the socket at the centre of the underside, working it back and forth to free the rotation. No wrench? A broom handle down through the sink opening, levered against an impeller, does the same job. Once it turns freely, restore power and press the reset.
Then find what caused it. Power still off, torch in hand, look into the chamber. Bones, fruit pits, a bottle cap, a spoon, or glass are the usual culprits — remove them with tongs, never fingers.
Where the fault is: the grinding chamber. This is one of only two questions where the appliance is genuinely the problem.
Where to stop: it still hums after freeing rotation, it trips instantly every time, or there's a burning smell. Those point at the motor.
Question three — does it drain? (It runs perfectly but water backs up in the sink.)
This is the question that saves people the most money, because the answer is almost always that the appliance is fine.
Grinding and draining are two different jobs. If the motor turns freely and it sounds normal, the disposal is working — and the restriction is in the path out: the discharge elbow, the trap, or the branch line beyond.
A two-minute test: fill the other side of a double sink and release it. If that side drains freely and the disposal side doesn't, the restriction is close by — the discharge or the trap. If both sides are slow, you're looking further downstream and the disposal is entirely innocent.
Where the fault is: the drainage, not the machine. Replacing the unit here changes nothing — you'll have a new disposal grinding perfectly into the same blocked pipe.
Worth knowing why kitchen lines block: a disposal doesn't remove grease. It emulsifies it and sends it warm into the branch line, where it cools on the pipe wall. That accumulation is behind most kitchen line blockages, and it's why cabling a grease line restores flow briefly while jetting actually cleans it.
Question four — is it holding water in? (Water appearing where it shouldn't.)
Dry everything thoroughly, run the disposal briefly, and watch where the first drop appears. Two minutes, and it decides whether you're buying a seal or an appliance.
- From the top, where the unit meets the sink — the flange seal or the mounting assembly. Repairable, and worth re-seating properly rather than tightening and hoping, because a loosening mount will do it again.
- From the side, at the dishwasher inlet — the hose clamp or connection. Straightforward.
- From the side, at the discharge tube — the gasket or bolts at the discharge flange, or the connection to the trap. Repairable, and often an alignment problem rather than a worn part.
- From the bottom of the unit — the housing has corroded or cracked. Not repairable, and this one is a replacement.