The hook on top of the mast also has a metal loop that that the halyard has to pass though to keep the hook from moving. I have good luck with just running the halyard though the loop on the ring and whipping it and then put a piece of heat shrink tubing over it (about a inch tail). When you hoist the sail go slow when you get to the top and you can hear the ring hook on the catch, don't pull the sail up too high as it just moves the ring out of the way. Last make sure the the top of the mast is in alinement with the hook as you can bend it a little to make it work better ( I had one that was very bad out of alinement).