How to remove the broken ball end of a small hex key that is now stuck inside the socket While trying to replace the yoke of my derailleur I made the mistake of using a multi-tool hex key that was not able to handle the torque necessary for the task and snapped while the head stayed inside.
I tried using gravity, a magnet, shaking and all combined to make the head fall down, to no avail. I've no idea on how to proceed further and am really thinking of getting a new derailleur.
Chances are you were turning it clockwise when it broke. By tapping it anti-clockwise with a small drift or cold chisel, it may unjam it, when a magnet along with gravity and tapping should release it.