I had trouble getting the ring off until I bought one of those "Aussie Halyard Rings" which has the little tie loop on the inside of the ring, off to the side a bit, instead of the outside top of the ring. I pass the halyard through, tie a stopper knot on the outside and it has worked great ever since.

Also, I make sure I park the boat at a slight angle to the wind, maybe 20-30 degrees off dead up wind, to hold the main to one side of the boat, then rotate the mast in the other direction, it seems to help get the ring off the hook. I've been getting it unhooked the first try with the new halyard ring where it used to take me 4-5 attempts with the old one.