Sending unit lock ring won't lock

I'm trying to get the lock ring back on the sending unit on my 71 Duster and when I put it on with the gasket, I can turn the lock ring by hand as far as it'll go and it never tightens. It's like the gasket is way too thin but the gasket I have is actually slightly thicker than the one that came off of it. I'm replacing the lock ring and gasket because it was leaking gas with the old one.

Anyone ever run across this before?

Make sure you didn't bend the tabs on the tank up when you removed the old one. If you did, lightly tap them back down with a brass punch(so you don't make a spark). Be gentle!

Same issue here.

Thanks for the tip GOTMEA73!

Later,
Bruce B.

its the only reason why

but be careful not to make a spark
when taping the little tabs

hade the same problem I solve it that way