To hook properly, apply Marine Goop to your shackle below the ring. You don't need much, do it on the ground, maybe with a little paper masking tape, and let it start to harden. Mash it back in place gently if it drips.
Once it doesn't drip- say 5 minutes, put the sail up, possibly turning the boat over. When the Goop is pretty hard, after sailing, it will work for months until it shrinks a bit-
Then just apply a little more Goop.
Up or Down- everything works now.


This is instead of the stupid rubber sponge that always moves and falls out.