While I was taking apart the engine to change a bad headgasket I noticed that there was a badly bent pushrod on the opposite head. I pulled that valve cover and the rocker was loose. The red stud holding to the arm was snapped in two. They are stock roller rockers and that arm in particular was closer to the number 5 cyl instead of 3 like it's supposed to be. What would cause this to happen and if I just replaced them would it happen again?