I was thinking the roundpen was maybe the best solution. If you get him going good there, where he canít pull you around or do anything like that, then maybe attaching the lunge line in the roundpen would make him more solid to the idea.
Zeus was doing the same type of thing, although he flexes nice and everything, he had learned to pull someone around before we bought him, and going into the lunging situation loping was bringing it back out in him. He wouldnít do it trotting, but as soon as you tried to break him into the lope. The roundpen fixed the issue.
Am I not your own donkey, which you have always ridden, to this day? Have I been in the habit of doing this to you? - Balaamís Donkey