Remove fabric on bottom of sofa. Pull strongly to remove the staples that hold it in place. If you need to, use pliers to do this.
Check to see if springs are compressed or stretched out. They may be smashed down flat or may be leaning to the side. Compare worn-out springs to new springs in order to determine need of repair.
Attach pliers to the spring. Use them to pull and twist worn-out areas bringing it back to its original coiled form. If this process does not work, continue to Step 3.
Purchase a new spring. Identify the worn-out spring and remove it by cutting ties with a knife. You will need to use pliers to disconnect it from metal wires as well.
Replace the old spring with the new one. Tie the new spring into place using a strong piece of string.
Replace fabric on the underneath portion of the sofa. Use a staple gun to secure it into place.