If you need to keep the detachable flash shoe operational (when cracking up), it calls for drastic first aid: use SuperGlue in the crack, followed by an all-around Araldite/epoxy 'paint'. Don't get any of the stuff around the knurling ring or underneath where the contact pin is; just enough to cover the crack inside and out. It will probably give a while of service after this.
Ok, I have plenty of epoxy around, and I'd rather keep this hotshoe working if at all possible, since examples of used ones are hard to find and usually cracked too.