It sounds to me like the threads may be galled, in which case I would take it to a dealer and let them deal with it. If the threads are truly galled, they should cover a replacement axel under warranty. Galled threads totally suck!
[I]When you think of the long and gloomy history of man, you will find more hideous crimes have been committed in the name of obedience than have ever been committed in the name of rebellion.[/I]
- C. P. Snow