See how to replace bulbs that are not working in your 2003-2006 GM vehicle. http://usedcarsit.com/gauge-light-bulb-replacement-chevy-buick-pontiac-c... contains written directions on how to do this and a list of items needed.
These direction may work for other GM vehicles as well. Instructions on how to replace stepper motors are in this video http://www.youtube.com/watch?v=gWELz904fj0
Chevrolet, Buick, Cadillac, Pontiac repair