That's the same one that came off back in March. Are bearings worn or take-ups getting loose or something of the sort? Seems like something might be unusually worn if it keeps walking off.
Heck of a ripper. Here in my company we have a shop guy who is basically dedicated to our shear upkeep. They are an expensive attachment to run! Operators do crazy things to them and its wild to see the carnage come back to the shop.