DG,
I had the same problem. I had "Set" but "Resume" didn't work. Took the switch apart. There was something loose or something like that, but with my Bull in China Shop technique, I broke it beyond repair. Got one at the dealer for $37. 50. I hated like heck paying that much for a small piece of plastic (well, there's a couple wires too), but with all my highway driving, it was a legsaver.