I was scared by a bad grinding sound coming from my relatively new garbage disposal. I called the manufacturer, Emerson Electric Company. They assured me that rarely they find a manufacturing defect in the garbage disposal (https://www.insinkerator.com).They suggested calling their local authorized service folks (MrAppliance.com/Germantown-md. The service guy (Prasantha A. Wanigatunde) came and took some ice cubes from our freezer and put into the garbage disposal and turned it on. The grinding sound came up and in next few seconds the sound became normal sound of a garbage disposal. We did not have to pay, the manufacturer would pay him. Prasantha who is an Engineer from Sri Lanka told me the ice crystals do two things for a grinding garbage duisposal:
(1) Sharpen the blades of the grinder and
(2) Cold ice keep the motor cold for it to not die.
What a lesson!