Curtain rods that use drawstrings on the side of the drapes are a type of traverse rod. Often children or guests will pull on the fabric of drapes not realising that the drape operates on a string. This can break the string, or the string can wear out from sun damage. Replacing the cord may seem a bit complicated at first, but the mechanism is actually a simple pulley system, and once you fix it, you will be able to fix any similar drawstring curtain rod problem.
Place a ladder close to your window, and remove the drapes by unhooking them from the master carriers and slides of the curtain rod system. Drapes are often quite heavy, so be careful, particularly with tall windows.
Remove the curtain rod from the curtain rod brackets. Most rods will snap or slide in behind small plastic doors. The ladder should bring you close enough to see how the rod mounts to the brackets. Be careful to unhook the drawstring from the tension pulley mounted to the side of the drapes.
Place the curtain rod face down on the table or floor. Your rod should have two rectangular plastic boxes. Mark the box closest to the table with an A. Mark the box closest to you with a B. These are called master carriers. The small white plastic loops are called slides.
Cut and remove the cord, including the knots. Use a utility knife. Discard the old cord. Thread new cord into the top hole on the right side of master carrier A. Knot the cord. Take the cord to the right and over the top pulley. Take the cord down and between the top and bottom pulleys. The cord will now be moving to the left.
Thread your cord through the bridge of master carrier B. Take your cord to the left and between the top and bottom pulley. Pull the cord through. Take the end of the cord up and over the top pulley and move toward the right. Find the hole on the top left of master carrier A, and tie the end of the cord to that hole.
Rehang your curtain rod in the brackets. Slip the cord into the tension pulley. If you don't have a tension pulley, install one now. A tension pulley is a small pulley that mounts above the bottom hem of the drape at the outside edge. Slide master carrier A all the way to the right. Slide master carrier B all the way to the left, and latch the cord into the back side of the carrier.
Pick up the cord slack by finding the knot on the right side of master carrier A. Pull the cord at the knot until all the cord slack is gone and the tension pulley lifts slightly (showing it is under tension). Tie a new knot as close to the master carrier A hole as possible. Test the curtain rod function by using the cord. Both carriers should slide easily from side to side.
Trim off the excess cord once you are sure the rod is operating properly. Hang your drapes. Start with the back master carrier. Thread the hole farthest out on the arm. Thread the drapery hook from the back to the front. All other hooks thread from the front to the back and should be evenly spaced across the carrier and then on each slide. Save the last two hooks for hooking into the bracket.
If your curtains catch on each other you may need to bend the metal arms of the master carriers slightly so that the fabric ends will pass each other. These become bent when children pull on the drapes.