Sometimes in the normal course of operation, a garbage disposal will develop a hole or crack in the housing body, causing the disposal to leak. This can happen for several different reasons -- something as simple as the natural aging process or something hard could have been spun into the side of the housing and cracked it. A new disposal costs about $100, according to 2010 prices. The disposal may be repaired with plumber's putty and duct tape, extending its life by another year or two.
Refrain from using the sink and disposal for 12 hours prior to repair. The drier the unit before the repair is undertaken, the more chance for success.
Pull out a chunk of the plumber's putty big enough to cover the hole or crack.
Soften the plumber's putty by hand until it is pliable and soft.
Insert the plumber's putty into the hole and smooth it around the hole on the housing of the disposal for an inch or so around the hole. For cracks, smooth the plumber's putty over the crack and extend it beyond the crack an inch or so in each direction.
Wrap the housing with duct tape over the spot with the plumber's putty and completely around the housing of the disposal. This will provide a greater chance of success for the plumber's putty to hold back any leaks.