Insert thescrewdriver under the end caps located at the ends of the two sling rails. Pry off the end caps and put them aside for later.
Remove the stretcher rods from the backside of the chair frame. Lay the chair on the ground with its backside up. Shrink the size of the dual stretcher bar by inserting the socket wrench into the slot on the bar and turning counterclockwise to shorten the bar. Insert the bar between the two sling rails and tighten the dual stretcher bar by turning the socket wrench clockwise. This will open the frame and allow you to remove the stretcher rods.
Remove the old chair sling. Loosen the bolts located on the underside of the sling rails by turning the wrench in a counterclockwise motion. Remove the bolts. Spray the sling rails with soapy water to loosen the splines that hold the sling inside the sling rails. Tug at the sling until it loosens and slides out from the sling rails.
Insert the two splines through the side tracks on the replacement sling. Push and pull the splines through the tracks until there is no excess spline showing on the top or bottom of the sling.
Slide the sling through the sling rails. Start with one spline and work it a few inches into the left sling rail. Slide the right spline into the opposite sling rail and continue with this motion to move the new sling into position. Once the new sling is in place, tug at the top and bottom of the new sling to align it in place. Clamp the sling to the top of the chair frame with c-clamps to keep it in place.
Replace the bolts that hold the splines in the sling rails. Turn the bolts clockwise with the wrench until tight. Insert the end caps onto the sling rail ends and tap them in place with the rubber mallet.
Flip the chair over and loosen the dual stretcher bar with the socket wrench. Insert the bar between the sling rails and expand the bar by turning the socket wrench clockwise. Once the frame is spread, insert the stretcher rod back into its holes in the sling rails. Tap the stretcher rod with the rubber mallet to ensure a tight fit. Release the dual stretcher bar from the frame by turning the socket wrench counter-clockwise.