gregE ACS like other manufacturers use a special hexagonal rivnut or rivet nut (in the olden days they were round and used to twist loose, I used to get this on many machines I tested back in the day).
It’s effectively a captive nut, which the bolt can then screw into…it’s not something you can really fit yourself as it requires a special tool. They are made of stainless and sometimes when fitting with the air tool, if not done absolutely right, they can break off, as it looks like yours has done. The real PITA is if they spin (which is why most changed to hex versions) because then you can’t remove the bolt. I remember having terrible problems with a brand new La Spaziale Vivaldi 2 because the bolt was doing exactly that and it was very hard to drill out!!
I personally think it will be fine…but do let ACS know. In fairness to them, it may have screwed in fine at the factory and then fractured during transit…which is more likely. My only question would be when you pulled the bolt out, the rivnut should have been on the end…so perhaps something else happened??
