Greg, I really appreciate the analysis and the advice. I was very aware of the zigzag of the pull, but I was blind to the sea-saw affect it had on my movement.
I have a relatively weak squat, and think that I don't use enough leg drive off the floor. After reading your post it looks like I overload the hamstrings because I don't use the quads during the pull. Would you suggest concentrated pulls with a flat foot and a fixed start to correct the mechanics?
Never send to know for whom the bell tolls; it tolls for thee - John Donne