My garbage disposal turns on but just hums. After following many of the suggestions found here I've got it to work... but only if I start the momentum (turn with a dowel). If I shut it off, I'll need to start the turn again. Help!

It is not safe to use this disposal. There are two windings in some electric motors. One for running and the other to start from a dead stop, yours is burned out. It is not cost effective to repair a disposal motor unless its under warranty.

If that disposal motor has a start capacitor then you can test it and if it's bad, replace it. That would cure the problem for pennies. See: https://dl.dropboxusercontent.com/u/...e%20Manual.pdf
https://dl.dropboxusercontent.com/u/...Electronic.pdf

Here is a picture of a disposal: Google Image Result for http://cynake.sandwich.net/Random/Garbage%2520Disposal%25201.jpg
You can see the start capacitor.