Peter, what may have happened with the tight examples of your new nuts- the people who make these things may have over-plated the threaded holes inside, thus tightening up the threads. This has happened to people who pretty-up the rear swaybar by plating it; then the sphere-ball ends for the swaybar doesn't fit! Try running a tap through the new nuts and see what happens (assuming they are the correct threads to start with, of course!)
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