It can be repaired once it fully breaks be roughing up the plastic where it snapped with an iron file or sand paper, and then applying Loctite Ultra Gel. The fix should last. I've repaired an M50x and a few M40xs in a similar manner with lasting results.
I actually don't recommend ordering a replacement from AT, the headband design has an inherent flaw, but Loctite should make up for it.
I actually don't recommend ordering a replacement from AT, the headband design has an inherent flaw, but Loctite should make up for it.