G'day again Rum I've got an idea of what you have now. If you are tieing the halyard to your twist shackle that holds your ring loosly you will have the Halyard around the stern side of the ring so that it pulls it onto the hook, once on you have no easy way to release it because you have to pull the sail a long way up from the hook but the top pulley wont let you. If it was mine I would buy a stainless steel welding rod and arc weld the shackle to the ring so that its fixed in position and you would have something like this photo. You shouldn't need the rubber this sail is a pushup sail with no halyard. If you dont have a welder any engineer will do it in 1 minute.
regards