How to fix cross-threaded derailleur hanger? I've removed my rear derailleur so many times that I think I messed up the hanger threading this latest time I reinstalled it. It's very hard to screw in, doesn't even go in straight, and now not even my hanger alignment tool screws in properly. Since my bike is so old, I just bent the hanger to account for the miffed threads and reattached my derailleur the best I could as a temporary fix. Now I want to fix the threads. I've since learned of some methods involving tapping the threads as well as drop-out savers:

How To tap and Clean Threads On Your Derailleur Hanger

                
            

How To Fix Derailleur Hanger With Stripped Threads

                
            

Based on my description, is it likely that I cross-threaded the hanger? If I need to resort to tapping, how do I determine the proper tool to use? Are there bike-specific tools or will pretty much any tapping tool work so long as the measurements are correct?
If its a replaceable hanger, simplest option is replace it. 

If not you might be able to repair it with a 10mmx1mm tap. If that does not work, a Helicoil type repair is possible. Its one of those tasks if you are not 100% confident you can do right first time you might be better off handling over to a shop (An engineering shop or well equipped bike shop) as it is possible to make it worse.

Refer Park Tool Basic Thread Concepts