Problem: when I click on the prop to move it, or even move it's dial, the ball's y goes to zero (drops to floor).

Sequence:

Place ball next to the head.

Select the V4 head.

Scroll down to "Browup-down"

Open the dependency editor on that morph.

Switch tabs from Value operations to Keyed Dependencies. (There are already two dependencies in place, for the r- l- morphs)

Click on "start teaching."

Click on the ball with the intention of moving it a little. Ball drops to the floor.