When your garbage disposal is jammed, you can usually clear the jam by rotating the impeller back and forth. Do this carefully, of course, ensuring that the product has no way of accidentally turning on while working on it. Some manufacturers include a slot on the bottom of the unit so you can clear the disposal without reaching in through the top with a broom handle. This feature may be included on models from manufacturers, and if so, it's easy to tell; just climb under the unit and look. If your garbage disposal has a disposal wrench slot, it will fit a 1/4 inch Allen wrench. The wrench may which may be found taped to the side of the disposal, so check before purchasing.
The brand InSinkErator makes a specialty wrenches that work for its brand disposals. The Jam-Buster is a hex wrench that rotates jammed plates inside. Other brands have their own wrenches, but there are generic disposal wrenches that can safely dislodge debris and food caught in the disposal shedder plates. Allen wrenches that are 1/4 inch long save the expense of buying a new wrench. But if you do not have an Allen wrench available, purchasing a universal disposal wrench is worth the price.
How to Use Your Wrench
Always turn off the switch and the breaker in the main panel that controls the garbage disposal before working on the device. If the breaker has tripped, be sure to push it all the way toward the outside of the panel until it clicks.
You will use your wrench to rotate the impeller back and forth to free debris. Crawl under the unit, and locate the small disposal wrench slot (a recessed hex-shaped hole) in the middle of the unit. This is where you will insert the wrench and use it as a lever. By rotating the counterclockwise for a few turns and then clockwise, you will feel the motor shaft spin.
If your unit has no slot for a wrench, insert the universal disposal wrench into the unit through the drain. A broom handle or wooden spoon may work for this as well, though the generic wrench will be more comfortable to turn. Push through the top of the disposal and use it to turn the impeller.
How to Clear the Jam
Remove debris that comes loose, using a pair of tongs. Never reach into the disposal with your hand, even if you're sure it's off. The cost of a mistake in disconnecting the unit could be your hand! Turn the breaker back on when the impeller rotates freely, then push the red reset button on the unit. On some models this button is on the side of the canister, and on others, it's on the bottom. Make sure the button stays in -- if it doesn't, turn the breaker off and on again.
Turn on the water, then switch on the garbage disposal. Repeat the procedure for clearing the jam if it hums but doesn't spin.