i remember the problem, but i didn't remember if it was the lock ring, or the retainer on the tank.
i have a new stainless tank that came with a stainless lock ring, but i haven't installed it yet.
i will have to compare both the ring and the retainer on the new tank to the old one, and watch closely for anything starting to bend or leak when i install the new sending unit, which is also stainless.