Slide on a pair of work gloves to protect your skin. Remove the couch cushions. Turn the couch over so you can access the underside carriage.
Slice the perimeter of the fabric underside carriage covering with a straight-edge knife. Pry off any staples holding the fabric into place with a flat blade screwdriver. Remove the fabric.
Inspect each spring. Notice springs that have maintained their buoyancy and those that are currently compressed. Grip a compressed spring with a pair of pliers. Pull the body of the spring apart to reshape the spring into its basic form. Repeat this process for every compressed spring.
Drill a 3/8-inch screw into the top left edge of the underside carriage frame if your springs are a zigzag -- or sinuous spring -- design. Tie a piece of twine around the screw.
Pull the twine tight over the first spring directly to the right. Tie the twine taught around the spring. Pull the twine tight over the second spring to the right. Tie the twine taught around the spring. Continue until all springs in the line of zigzags are tied with the piece of twine.
Drill a second 3/8-inch screw into the top edge of the right edge of the underside carriage edge. Tie off the twine to the second screw. The twine adds an extra layer of resistance to prevent the springs from sagging. Repeat steps 4 through 6 to the bottom row of zigzag springs.
Reattach the underside carriage fabric covering with an industrial staple gun. Insert one staple every 4 inches around the perimeter of the frame