I'm still new to DB after playing a slab for 30 years (and continuing). I do not have access to a teacher, so that is a non-starter. I have a couple of instructional DVDs (Rufus Reid and Todd Phillips), have been browsing this board, and have observed and sought advice from DB players in my area. As I understand it, the left hand fingering should be relatively effortless with the thumb essentially acting as a pivot. No squeezing should be necessary. I've been told, and Todd's DVD shows, that you should be able to finger notes without even the use of the thumb, just the weight of the arm (as by example , not as actual playing technique). HERE"s the issue: If I am playing mostly fingered notes (few open strings) and/or trying to play with any kind of speed I find my arm, specifically where the rotators are, becomes tired and sore. The soreness can often linger for a few days. Coincidentally, I find it pretty much impossible to finger notes without using the thumb for support unless I prop the instrument against my body at a weird angle. I think the two things are related somehow. I've tried different heights which doesn't seem to change things. Any insights would be helpful.