How can I repair my upholstered chair?

The springs in the base of a sofa are sewn onto the webbing to give support.
Unless a spring has actually broken, which is unlikely, it's probably just where the spring has become detached.
Turn the sofa upside down and remove the fabric on the base to reveal the springs. Don't cut the fabric if you can avoid it as you'll need to replace it afterwards.
Find the detached spring and sew it back into position onto the webbing. It should sit directly over one of the webbing overlaps.
Just put in a couple of stitches on each bar of the cross to hold the spring in place.
You can get waxed thread and a sailmaker's needle from your local cobbler. The sailmaker's needle has a curve which allows you to sew from one side only.
Basically just look at how the other springs are attached and you'll get the idea.

Big Softy
February 2007