No power

Check the fuse box/circuit breaker. And if the disposal is plugged into a wall outlet, check the outlet

On/off switch is defective

On continuous-feed models, check the wall switch. On batch-feed models, check the stopper switch

Overload protector switch is tripped

If the flywheel is jammed, free it. Then push the reset button

Flywheel is jammed

Free the flywheel

Motor bearings have frozen

Call a qualified professional. You'll probably have to buy a new unit

Not enough water

Run more cold water when using the disposal

Improper waste in the unit

Only dispose of materials allowed by the manual

Dull shredder ring or broken flyweights

Replace defective parts

Metallic object in the unit

Inspect the unit and fish out the object with tongs or forceps

Mounting screws are loose

Tighten the mounting screws

Flyweight is broken

Replace the broken flywheel

Motor is defective

Call a qualified professional