It could be the switch, but my experience with GM windows is that it is more likely either corroded contacts or a bad motor. Before getting a motor, you'll have to follow most of the instructions in the video and clean all the contacts you can find. I think Radio Shack still has contact cleaner. There are some good videos online about cleaning these types of contacts. If you do end up replacing the motor its fairly easy but be careful not to break the white plastic retainers that hold part of the door panel on. Also be prepared to get cuts while getting the new motor in place. There's not a lot of room to work inside doors.
