axle locknut

[Unverfehrt400ex]

Hey I was working on tightening the axle last night when i encountered a problem. as im tightening the nut just as i start to get it pretty tight the thing slips over the threads and gets loose again. Im figuring something is stripped out just not sure what. Any thoughts?

[tprender]

The threads on the male part worn down. Unscrew it from the nut part and flip it around and put it back together. What happens is that the threads are fine, not very deep and the tops of them are worn down from being taken apart a few times. It you get a set calipators and measire, you will see the same difference in the size on both ends of the male piece.