What size and brand grapple was on the tractor when this happened?
What other FEL implements do you use on your loader, brand and model?
I seem to recall but can't say where it was posted; a recent thread discussing how backdragging with fully extended loader cylinders can do extensive damage, including breakage, and if one then tries to lift the grapple, as in your case, the other cylinder would suffer what you show in your pics, failure too.
Maybe someone here can recall what thread I'm referring to?
What weight is your grapple unloaded?
Can you post some pics of your entire tractor and some of your other FEL implements?
One last, for now, question: what # of hours on your tractor?