My magnet came off during removal of the flywheel. Since the magnet was held on via contact cement, that's what I used to reattach it. So far...been working with no probs.
I am not familar with the west system so I can't give you an answer. Another poster mentioned contact cement. I would make sure you clean it the flywheel and magnet well if you use that. Also, try to get the gel contact cement. It stays on better.
