Truck Repair: NTCC-444, lbs torque, adjustment screw

Question
On two occasions we have had an injector rocker arm break at the adjustment screw (horizontally like popping the top off a jar).  Assuming adjustment is correct, what else might cause this?  Thanks.

Answer
Have not seen that often on any engine.You torque the injectors down now instead of the tappet tool & the in lbs torque wrench.If you need the procedure just write back. But before you run the overhead I would advise flushing the injectors to remove carbon from injector tips.If you dont you risk pushing carbon in the spray holes plugging them.