Testing revealed the threads on the rod studs for both rams were machined out of specifications. Specifically, the rod stud threads were not properly machined to measure the required 0.995 inch outside diameter (OD), but instead measured 0.950 inch OD. The rod stud is the portion of the rod that is turned down and threaded for the piston and retaining nut. The improperly sized threads reduced the surface contact with the lock-nut threads and the fastener’s holding ability.