Hovering is right, I think the NTSB finding is important (a bad servo half with failed plating and debris) but it may not really explain the accident. I have no inside word at all, and speak only for myself, but the servo valves on the S76 are double spooled, so that a jam will lead to that servo half going into bypass (sort of forcing itself off line) so no hardover or stoppage is probable. Therefore, while the debris is not good, it does not seem to explain the accident.
A stick jump check is a great idea on every runup (I do that all the time) and any suspect movement, clunks etc should be examined.
The servo system is truly redundant, but lots of structure on a modern helicopter is not. Cat A regulations refer ONLY to engine power and engine/fuel system separation.