Turn off the circuit breaker to the garbage disposal. This is a vital safety precaution to prevent injury while you check the appliance.
Unscrew the threaded nut that holds the disposal to the underside of the sink, below the cabinets, with a pipe wrench.
Tighten the two bolts that hold the blades in position at the top of the disposal with a nut driver. Check the plate below the blades, while the unit is disconnected, to determine if there are any foreign objects jammed between the plate and the blades.
Clean the threading on the flange below the sink with a rag to remove any grime.
Wrap the threads on the flange with plumber's tape.
Reconnect the disposal to the sink drain with the pipe wrench.
Turn on the circuit breaker to the disposal.
Press the red reset button on the bottom of the disposal to finish the repair.