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Gary, perhaps I was a little unclear in my original post.
I normally guide with the QHY5 on the W066 and image with the Canon20d on the VC200L. The setup rides on a Sphinx SXW. I guide with Guidemaster v 2.0.25 using the outputs on the QHY5 to drive the ST4 inputs on the Starbook.
This setup is built up and torn down each session but I do make sure I balance correctly...
I normally use exposures in the 2-5s range and RA guiding is always painless typically +/- 1" or so. DEC however can drive me nuts. Mostly I get what I expect - a slow unidirectional drift in DEC with corrections off, I set GM to apply corrections only in one direction (opposite the drift) and all is well. At other times I find that after I get a periodic signal on the DEC axis which can go from -ve to +ve. I have not been able to determin a pattern to this behaviour.
Now IF the starbook behaves the same way as the SkySensor2000 then an alignment of 3 or more stars will start to compensate for polar alignment errors and run the DEC motor. The Starbook does not have a polar unaligned mode so I do not have visibility of this behaviour or control over it.
I think this means that I should restrict myself to a single alignment point in the starbook and drift align the mount.
I am not certain that this IS the cause if my problem. It does seem to make sense that for a session where autoguiding is to be used the mount should not be allowed to perform DEC corrections, some mounts seem to have a special AP mode that (I assume) would do this, the starbook does not (at least to my knowledge).
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