This may not work for you, but I got Buck to stop pulling by simply not moving when he pulled. As soon as he moves back a step, than I walk forward, but not until he actually takes a step backwards. It works well. Usually if he gets to the end of the line, he'll feel the lead tighten and he'll step back. But you have to let her take the move backward, obviously pulling her back won't help. Once she learns that she doesn't get to move at all when she pulls, she'll stop pulling. At least, that's what happened with Buck. But every dog is different...
The only thing is that with this method, at first it can take forever to get anywhere! Stop, start, stop, start. :fadein: