Did the old cord break? If it did, 99.5% of the time, that causes a backlash that destroys the spring. So if the cord did break, you may as well take it all apart and check or replace the spring. Otherwise, if it is still unbroken, see that 1/8" hole in the rope pulley? Find a nail or something that will fit through it and keep it handy. Pull the rope all the way out and stick the nail through the hole. That will keep the pulley from rewinding. Now remove the rope handle, and grab hold of the knot at the other end of the rope and pull it out. Reverse the whole operation to put a new rope in. Note that the rope passes through a pin in the pulley, near the knot.
