Thanks Roger and Jase
I asked Jerry at Technical inovations and he said it was normal but his email reply confused me slightly and didn't answer my questions well enough (IMO) so I thought I'd ask the wider imaging comunity.
All three replies from guys on the SBIG group all say backlash (play) in the motor shaft is normal and that I can either remove it with the backlash compensation in the RF/focus software or when using it manually, as I am, just approach focus from the loaded direction.
Must admit, I would have thought precision repeatable "Robo" focus would have needed rock solid positioning not an approximation..?
Cheers guys
Mike