"My argentine instructor says that when you are to the left, like the woman is in ballroom, that you have broken connection and the lead disappears. I do feel the difference. How do I get the same electricity and body awareness that allows the same flavor of connection in ballroom dancing?"
You each have to improve your perception of the other. You can sort of accomplish connection by being firm, but it really works a lot better when you both "listen" to each other. Then the leader needs to be clear, but doesn't have to be forceful. Similarly, the follower needs to be clear in not letting her contact parts become inconsistent from her center (which would make it hard for her leader to tell where her center is), but she doesn't actually need to firmly hold a fixed position of her body.