Thanks Steffen
That may be part of the trouble, and it now works well.
However I also found heaps of backlash in the Dec drive, as well as mismatching of the worm drive for same; ie a lot of slop in the gears.
Adjusted same to get a smoother and less noisy operation and the whole system is running well.
GOTO now drives to target within FOV of a 5mm lens for a 120 ED Saxon 900mm; which is near my effective limit for useful magnification.
All I have to do now is tighten the focuser and I'm ready to race.
