NO No NO. Trying to chase the thread with a die will only result in screwing up the remaining threads. If it isn't 1/4-28 as suspected running a die along it will absolutleyruin the crank.Even if it is 1/4-28, and the treads on the end are damaged, trying to chase thethreads will most likely result in thedie establishing a different thread pattern. If the nut cant screw on, the die won't eaither an will makeits own path.

A close inspection will tell if the thread is damaged. If they are, a simple file is the best tool to use, Hold it at 30 degrees to the shaft, the same angle as the threads and file pushing the file to the center line of the shaft. Don't even do this though unless you can see that the threads are damaged. Idoubt that they are as rsieminski sates that a nutwill screw on three turns prior to binding. That indicates thestart of the threads are good and what he is seeing is an example of thread pitch being different. As pointedout eariller, the 1mm pitch and the 28tpi are very close and it would take just about three turns to take up the normalthread clearance.

Don't fix something if it isn't broke.

Don