There's a guy on ebay, out of Ct. who has 100% positive feedback who rebuilds them and replaces all stepper motors that are defective, checks them with the latest computer programs available....I myself have an '05 Envoy that I will be sending him after Thanksgiving...beats the $700 the local dealers want to do the same thing....the guy on ebay can do it, and have a 5 year warranty, for under $200.....