Thank you all for your comments and especially
Darren Wilson for directing me to Allparts : - )
My guitars are perfectly set up (I've been playing rock for 30 years!) it's just that I play in a lot of bars in Hong Kong where you walk out of 100 degrees heat into freezing air cond pubs. I find that even after stretching the strings and settling them for a day or so, the top E and B still move around quite a bit,even after aclimating to the cold air con. The fine tuners take ages to twiddle around to get the string in tune and then, half the time, I run of room to twiddle! Then, it's out wit the allen key, unlock, re-tune and re-lock. I also play a 52 tele and 'V' neck American Strat with trem and they're both fine because any tuning is done on the run and very quickly (no bolts to worry about) - - I don't even think abaout it. I just love my Jems - - they're like my three children so want to use them as much as possible. Maybe the tremolo springs take time to settle in? I have noticed that the angle of the bridge of my JEM7VWH (very new) has increased by a few mm so maybe that's the problem or maybe it just takes time to get used to micro tuners.
Thanks again all of you - I'll order the ferro nut that Darren Wilson pointed me to and see how it goes (I'll experiment on an old Jackson).
Steve