The hum is a motor with power and nowhere to put it, so the two cheapest answers here are both about freeing the thing it is trying to turn. Jammed flywheel or impeller is where 4 of the 7 causes on this page get settled without buying anything — about 15 minutes, no part needed [S1]. On a garbage disposal the complaint is the disposal hums but the grinding plate does not turn, and it arrives in these words: disposal hums but will not spin, buzzes but does not grind, dead after a jam or the reset button keeps tripping. Parts only come into it once those are ruled out: the completed repairs behind this symptom run $319–$580 [S2], against a replacement from $150.
Do this first (free)
jammed flywheel or impeller [S1]
high likelihood easy no part needed about 15 min
disposal hums but will not spin buzzes but does not grind
The hum is the motor getting power and failing to turn because something is wedged between the impeller and the grind ring. The fix is free: kill the power, fit a 1/4-inch hex key into the socket on the underside, rock it back and forth until the shaft turns freely, then press the reset. S1 warns that a stalled motor overheats in well under a minute, so switch it off within seconds rather than leaving it humming while you think about it.
foreign object wedged against the grind ring [S1]
high likelihood easy no part needed about 15 min
disposal hums but will not spin dead after a jam
A pit, a bone or a piece of cutlery pinned at the wall of the chamber. Remove it from above with tongs, pliers or a wooden dowel, never with fingers, with the power off at the breaker. Free.
tripped thermal reset button [S2]
medium likelihood easy no part needed about 5 min
dead after a jam the reset button keeps tripping
Every disposal has a red or black button on the underside that pops out when the motor overheats or overloads; pressing it back in restores power, and it costs nothing. S2's point is why the sample of paid repairs is small at all: the reset and the hex key exist precisely so most of these calls never become repairs. If the reset trips again the moment power is restored, the fault is real.
not a fault: residue in the chamber [S2]
medium likelihood easy no part needed about 15 min
dead after a jam
A disposal that smells has residue coating the chamber walls and the underside of the splash guard, where nothing rinses. No part fixes it. S2's method is mechanical rather than chemical: ice cubes and coarse salt with cold water, plus wiping the underside of the splash guard by hand, which is the step everyone skips. Drain cleaners are the one thing to avoid because they sit against the seals.
What a technician actually does
failed start capacitor [S1]
medium likelihood advanced $150–$450 installed about 60 min
disposal hums but will not spin buzzes but does not grind
The chamber is clear, the wrench turns nothing loose, and it still only hums. S1 is blunt that this is not a home repair and that the realistic path is a replacement unit at $150-450 installed. Time basis: no published duration, book estimate.
the source prices this as a replacement unit rather than as a part, because the repair is not a practical home job
seized motor bearings [S1]
low likelihood advanced $150–$450 installed about 60 min
disposal hums but will not spin
Years of use or rust freeze the shaft, so the unit hums under load and will not turn even with the wrench. Replacement, same $150-450 installed. Time basis: no published duration, book estimate.
priced as a replacement unit by the source, not as a part
blocked drain line (it runs, but water backs up) [S2]
medium likelihood advanced not priced about 60 min
dead after a jam
S2 singles this out as the row worth acting on: a disposal that grinds perfectly and then backs up into the sink is telling you about the pipe, not about itself, and running it harder packs the blockage. Grease is the usual cause - it goes down warm and coats everything downstream as it cools. Not priced here because neither source publishes a disposal-dataset figure for it.
the sources call this a drain problem rather than a disposal repair and do not price it in the disposal data, so no figure is claimed here
Repair or replace?
A disposal is one of the few appliances where replacement frequently wins, and the reason is structural: the motor is the appliance. Switches, wiring, mountings, splash guards and an undamaged jam are repairable. A burned-out motor, a cracked body, or a unit leaking from the housing seam instead of a connection are not, because replacing the motor means replacing everything except the mounting ring. With a new unit installed at $150-450 and a median repair at $385, a second visit is usually the point to replace rather than repair twice. [S2]
- Typical completed repair: $319–$580 [S2]
- Comparable new unit: $150–$450 [S2]
- Planning life used for the decision: 10 years
- The median repair ($385) sits close to the installed price of a new unit ($150-450), which is why the honest answer here is often a swap rather than a repair.
S2 puts disposal life at eight to twelve years in ordinary use; the decision below uses the middle of that
Run your own quote through the calculator — the same half-of-new-price rule with your numbers.