1995 GMC Van electrical contact problem

Initial start problem: I have to jiggle the steering wheel to get contact so it will start. Some times it will work and some time I have to keep working with it until it makes contact. I have taken it to my mechanic twice and they can not get it to default as I have. They can not find the problem. Can you help. I know it must be a simple electrical contact that is at fault. My battery and starter work fine. Thanks for the help