I have a High Standard (I dont know much about guns)to make it shorter so that it would fit in my safe, have changed to a handle, one of those that can be extended but in the process now the gun does not work, it does not load the cartridges onto the barrel. The part that moves up and down in form of a U, releasing the cartridge from the magazine tube and loading onto the barrell does not move, stays down. There must be a spring or something now missing. Could you please advise or have drawing. Much obliged.