original sender and retaining ring or aftermarket?

I have found the aftermaket retainers to be flimsy and actually distort causing them to slide off center.

also the raised or stepped portion of the sending unit helps center the assembly on the ring, this step is shallower on some of the repos, making it tricky to keep everything centered when securing it.

I used to always use a brass punch, but with the thinner stuff I have had more sucess with the correct tool, OEM retaining ring, and pulling the tank to be certain everything remains centered when tightening.