When I located the blades and started to examine things for the cause of failure I noticed that the screw holding one of the blade grips has a fair bit of play in it.
You can thread it all the way in finger tight and still wiggle it around. I never noticed the play as the head was pre-assembled and I just backed out the screws, added thread lock to the screw and re tightened them. It could have been not enough thread lock used and it vibrated out enough to let go or the wrong size screw from the factory.
This episode gave me a valuable lesson, never trust a pre assembled part and always check for any play in all the screws before assembly.
The black screw is the one I am refering to and holds the blade grip on the rod.
