when people first started using these halyard locks they had a small hinged top to them. Hoisting the main you'd pull it up o it lifted but didn't go past the hinged bit but when you wanted to drop it you'd pull it up a little higher so it would let the hinged bit drop back down and stop your ring engaging on the hook.

It is a bad description but it might trigger someones memory and lead to them posting a photo as this would fix your issue.