1) Remove the blind. Generally you just lifted off the screws it is hooked over. Sometimes you may need to listen or remove the screws first.
2) Using your utility knife, cut the lift cord at the point where it is attached to the head box.
3) Using the old court as a guide cut a new cord that is 3 to 4 inches longer than the old cord.
4) Roll up the blind by hand. Tie the two ends of the new cord to the head box, and feed the cord around the blind and over the respective pulleys.
5) Slip the equalizing buckle (from the old cords) over the pooled and, and retain the blind.
6) Adjust the buckle into the blind hangs level.