Quote - So the elbow pad is a gradient from green to orange.  when i try to 'add' or 'subtract' weight from any part of it... nothing happens.

I'm trying to learn this WM stuff myself, and struggling. It seems to me that you need to fulfill three conditions before "something will happen".

1. There must be a weight map in existence for the parameter you are trying to adjust. If there is not one , you can add one via the "Add" button.

2. The "Active" check box must be enabled. This is the one that usually catches me out.

3. The "Paint" button must be active.

4. The painting tool you are using must have its Magnitude set high enough to have a noticeable effect.

If you have checked all the above and still nothing happens, close the Joint Editor, then re-select the actor, and open the JE again. I have a suspicion that in PP2012, the JE might sometimes loose focus on what it is supposed to be doing, and need restarting.