Hi all,
Many, many thanks to the IIS community for your input and replies.
I did a test shot of M16 last night from my light polluted suburban backyard setup on a concrete surface with much improved results.
(It's only an 1hr of data, with minimal darks - but there's no field rotation).
Amazing, after doing all the usual unpack, setup, initialize, 1 star align, Phd drift align Az, Phd drift align Alt, recheck Phd align Az, 2 star align etc. calibrate, frame, focus, finefocus, in record time, (about 90 mins) - M16 was smack in the middle of the crosshairs on the goto, first time, just as it should be!
(I should have mentioned earlier it wouldn't work at all on sat night, probably as the alignment was so far off.)
Jon, I did notice the DX graph on Sat night, there was some, marginal movement, deftinately not a flat line as such.
Happy days, shame about wasting a night's imaging under a beautiful dark sky, but it's all a learning curve eh?
Cheers
Andy