The disposer motor is not replaceable—if the disposer motor is defective or worn out, you must replace the entire disposer.
Common
03 - Foreign Objects In Disposer
It is very common for unwanted materials to get into the garbage disposer. If you hear something banging around you can use a flashlight to try and locate the item. First either unplug or turn off the power to the disposal. Once the item is located you can use a screwdriver and needle nose pliers to remove the object. You can also grind up ice cubes in the disposal to help loosen up any stuck items.