It is jammed, and the hum is the motor trying to turn against something stuck. Turn the power off, free the plate with a hex key in the bottom of the unit, then press the red reset button. This is a five minute fix and costs nothing — do not call anyone yet.
Do this first, and do it in this order
- Switch it off at the wall, then unplug it under the sink. A disposal that starts while your hand is near the chamber is how people lose fingers. Never trust the wall switch alone.
- Look in the chamber with a torch. A bottle cap, a cherry pit, a twist tie, a small bone. Fish it out with pliers or tongs — never your fingers, because the shredder edges are sharp even when stationary.
- Find the hex socket in the centre of the underside of the unit. Most disposals ship with a small L-shaped hex key, often clipped to the unit itself. A 1/4-inch Allen key works.
- Work it back and forth until the plate turns a full revolution freely in both directions.
- Press the red reset button on the bottom. It pops out when the motor overheats, and if you skip this step the unit stays dead and you will think you failed.
- Plug it back in, run cold water, and switch on.
If it hums with nothing stuck
A disposal that is free to spin by hand but still only hums usually has a failed start capacitor or worn bearings. At that point you are replacing the unit — a mid-range disposal is affordable and the replacement is a straightforward swap if the drain plumbing lines up.
If it does nothing at all — no hum
That is electrical, not mechanical. Reset button first, then the breaker, then the switch. If you have the GFCI outlet under the sink that a lot of newer Florida kitchens have, check that too.
Why it jammed, so it stops happening
Disposals are not bins. The reliable jammers are fibrous vegetables (celery, artichoke, corn husks), starch that turns to paste (rice, pasta, potato peel) and anything with a pit. Grease is the other one — it does not jam the disposal, it coats the drain line downstream and comes back as the slow drain you deal with in six months.
Run cold water, not hot. Cold keeps fats solid so they get chopped and flushed instead of melting and re-coating the pipe further along.
The one that is not the disposal
If it spins fine but the sink backs up, the disposal is working and the drain line is blocked. Different problem, and running the disposal harder just fills the sink faster.