Just to say thanks to the advice on this board I was adjust the vacuum modulator (lots of threads on this topic ) on my current transmission a few notches clockwise which seems to have gotten rid of the 2-3 flare without harshening the shifts. Tranny had new fluid/filter ~3000 miles ago when I installed it and I topped it off with 200ml of fluid that it needed (while the oil was hot immediately after a 30 min drive) a couple of days back. No sign of leaks when I did the adjustment either so hopefully the 2-3 flare will leave me for a few years at least!