To BMbikerider: are you sure about the N2000, otherwise known as the F-301, being a "clone"? I'm almost sure they were all made by Nikon in Japan.
See here: http://www.mir.com.my/rb/photography...ls/slr8486.htm
There is a difference between the manual focus F mount and the auto-focus mount. The ring, where the screw from the auto-focus motor seats, is wider than the manual bodies. But, that doesn't explain your problem.
As said above, built quality for Soviet lenses varies a lot.