There is a big caveot on this. If there is any resistance at all in the cable, it will not push fully home, just flex against the force of you trying to push it in. I would advise against trying it if you dont have an engineer to hand. Your choice, but I speak from experience.
By all means try it with an engineer around, its important you know how to operate it in an emergency, especially fiddling with the guard. It should be periodically operated in any case, to ensure servicability.
Cheers XO