Okay thank you.Check to be sure the locking tabs on the tank aren't bent outwards or the lock ring isn't deformed where the tabs contact it. The ring should require a decent amount of "persuasion" with a hammer and punch to get locked all the way. Otherwise there won't be enough clamping pressure on the seal.
Same here. They aren't made correctly.You need either a good used locking ring or a NOS one. The aftermarket rings are no good from what I have found.