How can I straighten out a bent threaded rod?
I've been able to manually straighten Acme leadscrew stock in the past by bending it down against a rigid surface, and checking its straightness by rolling it along a piece of scrap window glass (guaranteed to be flat). Rinse and repeat until you either bend it to within an acceptable tolerance, or you ruin it and have to buy a new one--which in this case is no big deal, since the one you've already got is already useless for your project.