Garbage Disposal Humming But Not Working? Here’s the Fix

If your garbage disposal hums when you turn it on but the blades won’t spin, you have a jammed flywheel. The motor is working — it just can’t turn because something is blocking it. This is usually a 2-minute fix with a 1/4” Allen wrench.

This guide explains exactly what causes the humming noise, how to fix it yourself, and how to prevent it from happening again.

The Quick Fix (Try This First)

Turn off the wall switch
Find the hex hole on the bottom center of the disposal
Insert a 1/4” Allen wrench into the hole
Rotate back and forth until the flywheel moves freely
Press the red reset button on the bottom
Run cold water and test

That’s it for most cases. If this doesn’t work, or you need more detail, keep reading.

Video Guide

Video: “Fix a Humming Disposal!” by The BeefMaster

Why Your Disposal Hums But Won’t Spin

The humming sound tells you the motor is getting power and trying to run. The problem is mechanical, not electrical.

Inside the disposal, a spinning plate called the flywheel has “teeth” (impellers) that grind food against a stationary ring. When something gets wedged between the impellers and the ring, the flywheel can’t turn — but the motor still tries, creating that humming sound.

Common culprits:

Chicken or fish bones
Fruit pits (peach, avocado)
Silverware that fell in
Glass shards
Bottle caps
Hard vegetable stems
Corn cobs
Seafood shells

The good news: if it’s humming, the motor isn’t dead. You just need to free the jam.

Understanding How a Disposal Works

Knowing the mechanics helps you fix the problem faster.

A garbage disposal has three main parts:

Motor — Electric motor at the bottom that spins at 1,700-2,800 RPM
Flywheel — Flat spinning plate with metal impellers attached
Grind ring — Stationary ring around the flywheel with grooves

When you flip the switch, the motor spins the flywheel. Impellers fling food scraps outward against the grind ring, breaking them into particles small enough to wash down the drain.

The motor doesn’t have the intelligence to stop when something jams. It just keeps trying to spin, pulling more electrical current and generating the hum you hear. This is why you shouldn’t let it hum for more than 10-15 seconds — the motor can overheat and burn out.

Step-by-Step Fix

Safety First: Turn off the wall switch AND the circuit breaker before working on a jam. Never put your hand inside the disposal, even when the power is off.

Method 1: Allen Wrench from Below (Best Option)

This method gives you the most leverage and works on nearly all disposals.

Step 1: Locate the hex socket

Look at the very bottom of the disposal unit. You’ll see a hex-shaped hole in the center, about 1/4” across. This is called the flywheel rotation hole or service socket — it’s specifically designed for unjamming the disposal.

Step 2: Insert the Allen wrench

Use a 1/4” (6mm) Allen wrench. Most disposals come with one in the box — check your junk drawer or under the sink.

Where to get one:

Most disposals include a wrench taped to the unit
Hardware stores sell them for $2-5
InSinkErator sells a “Jam-Buster” wrench
Any Allen key set usually includes 1/4”

Insert the wrench into the socket until you feel it engage with the flywheel shaft.

Step 3: Rotate back and forth

You’ll feel resistance where the obstruction is stuck. Work the wrench back and forth like you’re trying to loosen a stubborn jar lid:

Push clockwise, feel the resistance
Push counter-clockwise, feel the resistance
Repeat, gradually increasing your range of motion

After several back-and-forth motions, you should feel the flywheel break free. Keep working until it rotates freely 360° in both directions.

Step 4: Remove the obstruction

Shine a flashlight into the disposal from above. Use pliers or tongs to grab and remove whatever was jamming it. Never use your fingers — even with the power off, the impellers are sharp and the flywheel could suddenly move.

Common items you’ll find:

Bone fragments
Fruit pit pieces
Small utensils
Glass shards
Twist ties or rubber bands

Step 5: Press the reset button

The small red (or black) button on the bottom may have popped out when the motor strained against the jam. Press it firmly until it clicks.

If it won’t stay in, the motor may still be hot. Wait 15 minutes and try again.

Step 6: Test the disposal

Turn on cold water, restore power, and flip the switch. Run the disposal for 30 seconds to clear any remaining debris.

Method 2: Wooden Spoon from Above (No Allen Wrench)

If you don’t have an Allen wrench handy:

Insert a wooden spoon handle into the disposal from the top
Press against one of the impeller blades (the fins on the spinning plate)
Push to rotate the flywheel manually
Work it back and forth until it moves freely
Remove debris, reset, and test

This method works but gives you less leverage than the Allen wrench approach. If you can’t free the jam this way, find a 1/4” Allen wrench.

Method 3: Use a Disposal Wrench Tool

Some manufacturers sell special disposal wrenches (also called disposal tools or jam busters). These are essentially offset Allen wrenches that give you better leverage than a standard hex key.

InSinkErator Jam-Buster Wrench
Waste King EZ-Mount Wrench
Universal disposal wrench (fits most brands)

These tools are helpful if you have recurring jams, but a regular 1/4” Allen wrench works fine for occasional use.

Troubleshooting: What If It Still Hums?

If you’ve cleared the visible jam but the disposal still hums:

Check for additional obstructions — Sometimes multiple items are stuck. Look carefully with a flashlight and check around the entire perimeter of the grind ring.

Verify the flywheel is truly free — It should spin a full 360° with minimal resistance. If it catches or sticks anywhere, keep working it.

Wait for the motor to cool — If the motor overheated from humming too long, it may need 15-30 minutes to cool before the reset will engage.

Try the reset button again — Press firmly until it clicks. If it keeps popping out, the thermal overload is still active.

Is Your Motor Burned Out?

If you’ve cleared the jam but the disposal still hums but doesn’t work, the motor may be damaged.

Signs of a burned motor:

Burning or electrical smell
The disposal hummed for a long time, then went completely silent
Reset button won’t stay in even after clearing the jam
Unit is 8+ years old with multiple previous issues
Visible smoke or scorch marks

If you see these signs, the disposal likely needs replacement. Motors can’t be repaired economically — a new unit costs $80-300 plus installation.

For a complete diagnosis, see our complete troubleshooting guide.

Prevent Future Jams

Once you’ve freed the jam, take steps to prevent it from happening again:

Always run cold water before, during, and after using the disposal. Cold water keeps fats solid so they get chopped up rather than coating the blades.

Feed waste gradually — Don’t dump everything in at once. Feed scraps slowly while the disposal runs.

Avoid problem items:

Bones larger than chicken wing bones
Fruit pits (peach, avocado, cherry, mango)
Fibrous vegetables (celery, corn husks, artichokes)
Pasta and rice (expand with water)
Coffee grounds (build up over time)
Glass, metal, or plastic
Grease and cooking oil

Run the disposal regularly — Even if you don’t have much waste, running it prevents rust and buildup on the impellers.

Clean monthly — Grind ice cubes to clean the blades, then citrus peels to freshen. Or use baking soda and vinegar.

When to Call a Professional

Most humming disposals are an easy DIY fix. But consider calling a plumber if:

The jam won’t clear after multiple attempts
You smell burning (motor damage)
The reset keeps tripping immediately
You’re not comfortable working under the sink
The disposal is hardwired and you can’t cut power

A plumber can diagnose whether the unit is salvageable or needs replacement, and handle the installation if needed.

FAQ

Why does my garbage disposal hum but not work?

The flywheel is jammed. Something is stuck between the blades and the grinding ring, preventing rotation while the motor runs. Insert a 1/4” Allen wrench into the hole on the bottom of the disposal and rotate back and forth to free it.

How do you unjam a garbage disposal?

Insert a 1/4” Allen wrench into the hex hole on the bottom center of the disposal. Rotate back and forth until the flywheel moves freely. Remove the obstruction with pliers (never your hand), then reset your disposal and test.

How do I know if my garbage disposal motor is burned out?

Signs include a burning smell, the unit going completely silent after humming for an extended time, or the reset button refusing to stay pressed in even after clearing any jams.

What size Allen wrench for a garbage disposal?

1/4 inch (6mm) fits most disposals including InSinkErator, Waste King, Moen, and GE. Many units come with this wrench in the box — check your junk drawer or the cabinet under the sink.

How long can I let a disposal hum before it damages the motor?

Try not to let it hum for more than 10-15 seconds. The motor draws extra current when stalled, generating heat that can damage the windings. Turn it off, clear the jam, then try again.

My disposal has no hex hole on the bottom. How do I unjam it?

Some older or budget models lack the service socket. In this case, use a wooden broom handle or dowel inserted from above. Press against an impeller blade and push to rotate the flywheel back and forth until it breaks free.