So I spent some quality time with the mount last night...
The first thing I did is to try the autotracking. I couldn't ask for better performance. In CCDSoft, the error reported was 0.2 pixels max over a 20 minute guided exposure. So I figured this must have been a software issue.
Next I ran pempro to do a polar alignment. That took the better part of 4 hours..It seemed that I either overshot one axis or the other. After struggling with this it seems that the best I could do was a drift over 5 minutes of 40 arcsec in azimuth and 15 arcsec in altitude (yes arcseconds). This seems to allow me to do a 10 minute unguided shot without a problem.
I then did a pempro PE analysis on the mount. The results were spectacular, and error of 1.8 / 1.1 arcseconds. This was reproducable.
However, I then wanted to start using the mount for an image. So I slewed to an object and tried to turn on autoguiding. Well it picked up the star fine but after the first correction the star was gone.
So I did a recalibration and it was now impossible to recalibrate the software.
What happened was this: The N, S, W movements were perfect. The star image afterwards showed that it moved perfectly in the initial move and the return. The E movement was another story!
When CCDSoft takes an image after moving, the stars are long trails. It seems that in the E direction the mount keeps moving after the correction is sent.
Now, I can reproduce this manually. In the autoguide screen of CCDSoft there are the N,S,W,E buttons to move the scope. If I press on the E button and take an image, the mount is still moving. At this point if I do "Take image" again, it is still moving! and again! Then it stops.
So it seems like the mount is getting the command to move and it is then taking 8 seconds or so to complete it, and we are talking a small amount of movement.
Now get this. I went and slewed the scope around randomly for about a minute and then tried to calibrate again. This time it was perfect! So for the next 40 minute all was well, then I went to bed.
So, where do I go from here?