OK, final post. All of the grounds are connected together, and connectivity tested with a meter. The controller board has pull up resistors on SDA and SCL included, although they are 10K and most docs I could find say 4.7K is ideal.
So I've got better things to do with my time. I'll go back to the software servo control, probably using something similar to the "sensor shield" so I'll have the 3 wire connection. Someday when I've gor everything running and I'm bored, I'll go back and pursue the problem just out of curiosity.
Bye for now.