Thanks to those that responded to my problem. I finally called a MinnKota technician and he told me what to do. There is a small notch (more like a nick) on the outside of the lower unit casing. You really have to look hard to see it. That notch has to be down, towards the skeg in order for the motor to turn in the right direction. The way it is designed, when you install the motor it is either up or down. In the four times I had the thing apart, I never, by chance, got lucky and reassembled it correctly.
Dave