I have been aware for a while that there was evidence of some flexure between the guidescope and the main scope but never seemed to be able to pin it down. This now appears to be because I was taking it for granted that the four finger screws that secured the main scope to the mount were doing their job. However after giving everything a really thorough going over I was surprised to find the thread had stripped on one of these screws and there was a tiny amount of movement twixt the scope and the mount. I'm now wondering how long this problem had been present and how much time I had wasted trying to get the guiding software to compensate for something I should have remedied much earlier. Although the moon is now present a quick test last night proved that replacing the faulty screw had brought a noticeable improvement so another lesson learnt the hard way!