I have had partial success in resolving issues moving actors along paths where they started part way through the path. I was using asy 25-100, 100-75% where I should have been using 25-100, 0-75% I seem to have got cofused with the frames which were in the order of 0-99. I still have problems on more complex drawings following paths with multiple actors, I don't know if it is a function of graphics card, Reddsk, GUI or finger/brain interface. I tried simplifying the drawing as you requested and removing many f the actors solved the problem but dthat oes not alter the fact that I need them in the end drawing. Unfortunately I am unuble to publish the drawing at present or I would do so to allow you to see the problem in all its glory. I shall try and produce a drawing with a simillar problem over the weekend.
Thanks for your help.