what's the least painful way to fix garbage disposal?

depends what it's doing. if it hums but doesn't spin, it's jammed. kill the power first (unplug it or flip the breaker), then look underneath in the middle of the unit for a little hex socket. a 1/4 inch allen key fits it, and most come with one. work it back and forth until it turns freely all the way round, then press the red reset button on the bottom and try again. if it does nothing at all, not even a hum, try that reset button before anything else. it trips when the motor overheats. never put your hand down the drain, even with it off. tongs for anything stuck in there. and if it's leaking from the body of the unit rather than a pipe joint, that's the end of it, replace it.