[Tony_ (Tony)]

I've had a few problems lately with guiding, this is the current one that I want to resolve.
CGEM mount, SCT9.25", ST80 guidescope + celestron nexguider.

I keep getting regular movement creating double stars. The movement is is the declination direction (elongation in the RA direction is my next issue). The movement is fairly cyclical - average every 9th image (30 second exposures). Also the 2 images are quite discrete - so the movement from one point to the other is quite fast. Maybe some sort of backlash issue - but that doesn't explain the cyclical nature? Overall movement in RA is cyclical but the dec should be more or less random?

Note: I think polar alignment was very good - there was virtually 0 drift over 4 hours (GOTOs still centered). Also I didn't seem to have any flexure issues.

I am thinking the solution may be to not have the balance too good in the declination? I usually have it balanced as well as possible - but now I think maybe I should have some excess weight at one end - what do you think? I've read that it's best not to have the balance too good in RA either - how much out of balance should it be?

Any other ideas?

Regards,
Tony.