[Mart]

A new, or good condition used nut should run down the full length of the threads freely. If the nut stops, it means the threads are either damaged or filled with crud. Bits of old thread or dirt. Give it a good wire brushing by hand and inspect it carefully using a magnifying glass if necessary. If I were you I'd buy a new nut if they are available locally and cut it in half. I'd put the nut halves around the base of the threads and clamp it on. I would then lubricate it and wind it off the thread while clamped tightly together. If there are any burrs on the axle this ought to straighten them up. Ok I know the axle is good quality and semi hard, but for the cost of the nut I'd give it a go regardless.

Mart.