If you do decide to change them yourself, make absolutely sure that when you start to wind the springs that: #1, the winding bars are heavy enough to do the job, #2, you place yourself on the spring side of the hub (the spring will get shorter as you wind and you don't want to be in line of the hub). If a winding bar comes out of the setup, it will be a bullet and the spring will lengthen like a shot.