OK, the solution to this one is either a quick fix or a total replacement. The problem is caused by either:
In most cases a humming noise will be caused by a stuck flywheel. The sound won't last long as the disposal's reset button or the circuit breaker / fuse protecting the garbage disposal wiring will trip to protect the circuit. To determine what is causing the humming sound, let's start with the easy possible problem, a stuck flywheel.
- To start the repair, turn off power to the garbage disposal at the electrical service panel.
- Reminder: Don't ever put your hand down into the garbage disposal hopper (grinding chamber).
- Take the offset wrench that came with the disposal unit and insert the wrench into the flywheel turning hole in the bottom of the unit. If you don't have the wrench you can pick one up from the hardware store that sells your garbage disposal.
- Once the wrench is inserted, turn it clockwise to dislodge the stuck impeller or flywheel. When it dislodges, you'll feel the flywheel turn freely.
- Another approach is to try and use a wooden broom-handle or similar wooden object to free the stuck impeller and flywheel from the top of the unit through the drain.
- Place the broom-handle into the hopper and against an impeller. Use leverage to try and free the stuck flywheel. As before, when it dislodges you'll feel the flywheel turn freely.
- If the flywheel was not stuck and the unit is humming with nothing in the grinding chamber, then the garbage disposal's motor has seized or has one or more frozen bearings.
- If a bearing is seized, then the garbage disposal needs to be replaced.