And of course one thing we don't know is exactly what the total inherent feed back forces are.
Testing during design may have shown up that the forces could exceed the design of the rotating control elements. As I said above the force of the spherical bearing has to be overcome as well.
Easy fix - don't make the control hydraulics tough enough to break things. Let the single units feed back and the dual units with a "LIMIT" indication.
This has been flogged to death
here.