Fibrous materials, particularly banana peels are the worst thing to put in a garbage disposal.
A garbage disposal is like a rotary food processor. It has small grinding ports open on its sides that grind the food particles. When the ports become clogged, most conventional cleaning methods don’t work. Drain cleaners do not work, because they just flow out the bottom without ever contacting the ports. Plungers don’t work because a few open ports will vent all the plunger pressure.
Try filling the disposal with ice cubes, turn the cold water on medium flow, and turn the disposal on. The grinding ice will clean out the clogged ports and return the disposal to like new working order. It will make some noise, and you may see food particles break loose and come up through the drain. No problem, it will work fine afterwards.
Avoid the fibrous waste in the disposal.
[Edited by Rick on 25 February 2001]