Usually on these when the motor goes bad it seizes up. If you listen closely after the unit fills you will probably hear it humming. Occasionally it will just be a piece of debris jammed in the chopper blade. You can access and repair this by taking the pump apart from the top. However if you remove the kickplate and look directly underneath the center of the pump/motor assembly if you see a little pile of rusty soapy residue on the floor the motor is done.