Thanks very much. I have the Rufus Reid DVD and I will do as you suggested.
A slight follow up if I may - Any guidelines (conceptual, or to check in a mirror) for proper shoulder technique and general posture in thumb position?
I pulled out my copy of Ray Brown's Bass Method book. There's a picture of him on p. 10 up in TP where both elbows are extended quite far away from his body, almost forming a diamond shape w/ his head at the top and his hands on the bottom. But his shoulders appear to be relaxed, level, and not hunched or shrugged as you outlined. A little hard to tell since he's wearing a suit. He is leaning quite far over the front of the bass in this picture, bent at the waist it appears to me.
Thanks for any additional info you'd care to provide.