Thanks for the help. The threads are tore up and the nut want spin freely onto the stem. I am most likely going to have to rethread it.you can use a millimeter rule to measure the diameter and count threads
a wire wheel will do most of the cleaning needed in the threads
I agree. The damage that we see on the third thread from the top should make it difficult to install the top nut. The fact that the nut turns freely suggests that it is the nut that has problems.the threads don't look that bad to me in the pic - i'd try cleaning first before removing metal - there isn't much there to begin with