Had a new lesson last friday, and it went pretty well.
Unravelled how I was leading a cross, which was forcing a leg extension by my follows: I was coming into the last step (together for me, cross for the follow) with too much energy, sending the back leg out and around.
Eliminating that extra energy, and focusing on closing with the right shoulder after the cross, there is now a very nice little pivot possible at the end of the cross. It feels nice!
After that, though, we tried to make my dancing a little less soft. I (and, as I'm told, many Americans) dance with a very soft style. 'Soft' is probably not descriptive enough, as it includes a lot of things: precision in steps, directness of movement, machones in attitude, walking technique ... as it happens, I don't dance a lot like an (mythic or idealized) Argentinean.
So I have been working on this a little, and it's hard work. I actually don't want to change entirely - many people like the softer style. I would like to have both available to me, though, as dictated by partner, mood, and music.
Lots of interesting discussion of technique, as well as videos of dancers here. As far as I know, the most comprehensive on-line source for Tango videos (well, except for youtube, perhaps) and discussion. I have tried before to walk more straight-legged, but it never seems to work quite right with my body.