I had to pay for this info when this problem happened to me several years ago, but I feel that people should not have to be taken advantage of when it comes to the repair work of the car.
Step 1: How to Repair a GM Speedometer
1. Soldering Iron
3. Needle nose pliers
5. Solder bulb
6. Regular Kitchen Fork
1. Replacement Stepper Motors -
Available from Dr.Speedometer in any quantity, $6.00 per motor + $5.00 shipping. Use this link to order: http://drspeedometer.com/stepper-motors
If the link doesn't work, you can google gm replacement motors or Ebay it
Example speedometer is from a Silverado. Yours may vary in appearance, but the procedure is basically the same for all 03-06 GM instrument clusters.
I used the same procedures for my 2004 Impala