In this case the loose nut was me behind the ST 16! I had it all worked out. Set the height beforehand in the GUI to 55 metres (local rule to film over this steam railway) . So straight up in hare mode no need to check. Lined up to get straight got the train coming toward and the idea was to track sideways and descend whilst turning the Knurled K1 knob to keep the train in shot. Oh dear put the pan mode in global so the camera kept on turning by which time I had lost all orientation.The result was a disaster the old trains only come every two hours and I did not fancy the wait. I must set it up as a CCC which should let me concentrate on the camera.