Many sofas are made from sinuous, or S-shaped, spring bases to help add bounce to the bottom of the couch. The sofa cushions sit on top of this springy base to add comfort while sitting. Over time, the springs may become loosened or even break. When this happens, if the rest of the sofa is undamaged, then it is a simple process to repair the springs to restore the sofa to usefulness once more.
Remove the sofa cushions and pillows and set them aside. Flip the sofa over so the back is exposed. Most of the sofa springs are easily accessed from the back side of the sofa. Remove the staples or nails holding the back cover over the sofa frame. Pry the staples up with a screwdriver or pliers. If you cannot unhook the back of the sofa, then cut it off with scissors. You can replace the sofa backing easily with sewing supplies later.
Inspect the sofa springs. Most sofas use sinuous, or S-shaped, springs laid across the bottom of the sofa. Repairs may be necessary if the spring has loosened or broken. If the spring is broken, then it will have to be repaired by a professional upholster. You can also replace the entire row of springs yourself by ordering a replacement spring online or from an upholstery shop.
Remove the troubled spring from the back of the sofa if it is broken. If it is attached to the sofa frame, you may have to cut it out with wire cutters. Slip the new spring into its place.
Attach the new spring to the sofa frame with baling wire. Tie the wire around the springs tightly to hold the spring in place. Reinforce the bond by tying it into place with heavy twine.
Leave the spring attached to the sofa if it is sagging and not broken. Use the pliers to re-bend the spring to match the shape of the other springs.
Make a splint for the damaged wire from wire hangers. Bend the hanger into the same shape as the original springs. Tie the hanger splint to the weakened spring with twine. Wind baling wire around the springs, and attach it to both sides of the frame to create additional bounce.
Replace the batting and backing on the back of the sofa, staple it into place, and flip it back over. The springs should now work as they did when the sofa was new.