If your couch starts to sag or you feel metal poking through, you may need to replace the sofa springs. Changing old sofa springs can be difficult, but it can give your couch years of renewed life. Consider changing your springs if you have a couch you love that has lost its comfort.
Remove the staples and fabric that cover the bottom of the sofa to expose the jute or webbing where the springs are attached.
Remove the stitches holding broken or worn springs in place with a seam ripper or scissors. Remove the broken spring by twisting it through the webbing.
Place the new spring where the old spring was. Use a half round upholstery needle and strong thread to stitch the spring into place where you removed the previous springs' stitches. Make several strong stitches and knot the thread to hold the stitch in place.
Repeat steps 2 and 3, replacing each spring one at a time until all worn springs are replaced.
Re-staple the bottom fabric back in place.