Window blind strings kill a child every two weeks. Window blind strings manufactured before 2001 pose a serious threat to child safety. Starting in 2001 string manufacturers started adding safety features like breakthrough string tassels and vertical blind tension weights. The breakthrough string tassels snap with excessive pressure and the counter weights help keep the continuous cord from twisting and tangling. The safety equipment used can not make vertical blinds 100 per cent childproof. Vertical blinds manufactured prior to 2001 can have the strings replaced with safety-style strings.
Remove the vertical blind's louvres from the plastic retaining clips found on the headrail. Grab the louvre near the top and gently push up until the louvre's locking hole opens the louvre retaining clip. Slide the louvre to the side and pull down. Set the louvres aside.
Pry a mounting bracket's retaining clips away from the headrail with a flat screwdriver. Pull down on the headrail and continue to the next mounting bracket. Keep a hand on the vertical blind's headrail while working from one side to the other.
Lower the vertical blind's headrail to the ground.
Remove the plastic inserts on both ends of the headrail. Depending on the model, use a flat screwdriver or the proper size Allen wrench to remove the set screws. Check inside the headrail's track for the set screw.
Thread the vertical blind's string, from the pull-cord side, through the hole in each retaining-bracket's carriage. Use needle-nose pliers to pass the string between each carriage.
Pull the string out from the last retaining-bracket's carriage, past the same side of the pulley and out the far end of the headrail.
Push the string back into the headrail, around the pulley, and between the carriages and the back of the headrail.
Pass both strings through the top holes on the vertical blind's carrier and out through the bottom. The carrier, found at the end of the carriages, pushes the retaining-bracket carriages to the open and close positions.
Tie knots in the ends of each string as close to the carrier as possible. Cut the excess string from the tag ends with scissors.
Set the draw string or chain on the pull-cord pulley wheel and install the cap. Replace the set screw. Install the other cap.
Close the carriages with the pull-cord. Gently tug on the cord. The gears will slip into the correct position.
Install the headrail in the mounting brackets. Install the vertical blind's louvres.