The problem and instructions for replacement can be found here:
http://www.gaownersclub.com/kbruce/m...ec_16_2004.pdf
It is actually a pretty simple fix if you have a small socket wrench and a screwdriver.
You can get the parts for under $30 from either of these places:
www.gmpartshouse.com
www.gmpartsdirect.com
The part number for my 1999 was 10359040, but yours may be different depending on the year of your car.
Hope this helps