i have some thread files from mitchell that will fix almost any type of screwed up thread. they were expensive but have saved me many times. It may not have helped here but they are good for things like this.
Another trick I use on things like this is to leave the nut on the last few threads so they can't compress/distort. Sort of like when you whack a ball joint or tie rod end and ruin it when it wont come free.
Winter White 9-7x