Thanks Adam and Fred.
Yes-I can hear 'shunting' noise-which I imagine is the 'Push-Pull' you mention.
The RA is fairly well balanced,so will unbalance the as you mention.The DEC
is a bit unbalance-as when the camera is racked out to focus,is heavier that end,I will balance it properly if you think that would help.
Also,I have yet to properly set the B.L comp on the paddle,So all of this is not a major thing to improve on.I am hopping such actions will improve the issue.
Not sure what else to do if these actions do not improve it.I did do a ten minute exp of M 83 a couple of months back,and it was quite good.it was almost overhead.
Thanks for help-Chris
PS I'll post an image from last night to show trails as it came out of camera (if I can find it in the bin)