Fred the cocking rod is held in place by the lifter which is peened at the end of the cocking rod. Very possible the lifter was replaced and not peened to keep it from coming off the cocking rod.
You will have to take the lock plate off and then you can see what is happening. You will have to put the receiver vertical with the cocking rod held firmly in a vice or a way that the cocking rod will not move. A center punch placed between the lifter and cocking rod and struck with a hammer in a few places will keep the cocking rod and lifter in place.
If you have any questions please let us know and will guide you through it.