I have personally replaced many disposals for friends as well as mine over the years. Posts are correct using the wrench and/or reset button. Once they leak, replace.
A new unit is needed. Not more than 1/2 horsepower motor.
What puzzles me is a vent pipe. Have never seen one before. Don't know why it would be needed under the sink. The pipe behind the wall should be vented outside, usually to the roof. I would be worried about sewage gas. Just saying.
