It is necessary in the interest of safety to point out that removing and replacing the main spring is under no circumstances any where near as easy or safe as presented in the following pages from Edison. You must really have strong hands and endurance to get all the way through it and if it slips away from you, injury can result. It is better to send the spring barrel off to a professional. I have done a few myself, but I do not recommend this to anyone. If you must do it yourself and decide that the large risk of serious injury is less important than parting with thirty or so dollars to let a professional do it, then good luck. You will need it.