I've got an old pin lock that leaks from around the lid (a lot). I received it this way (for free). I've tried keg lube, I've swapped lids, I've used extra fat O rings, and even tried to bend the mouth of the keg to seal. Nothing works. I'd like to use it, as I don't want to buy a new-to-me one. What do I do? Can I weld the lid shut? Would I have to convert it to a sanke?