w7ay
Chen, thank you for your suggestions.
w7ay (1) When you did these measurements, what was the guide camera's angle? Is it possible to redo the measurements so that the declination axis is almost parallel to the camera's x- or y- axis?
Yes, the guide camera RA angle from the PHD guidelog was -176 so it would seem that the difference is only about 4 degrees from x/y. This I can confirm as when the calibration happens, visually the E movement is along the horizontal axis more or less.
w7ay (3) You might also try to balance the instrumentation on the declination axis as well as you can.
I have done that already. After the first set of measurements, I checked and found the scope was very back heavy. I then added a dovetail conuterweight in front and used the same pencil approach to keep its CoG approximately over the dec axis. It did seem to improve a bit, but not enough (I feel) to distinguish from seeing differences.
However, it is not well balanced in the 3rd axis due to a filterwheel which is at an angle. There is an OAG on the opposite side, but the FW is obviously much heavier. i suppose I could try that. Though the Redcat 51 had the same filterwheel at a similar angle as well.
w7ay (2) For what its worth, there is one major difference between pier-west tracking and pier-east tracking.
As of now, this seems to be about the only possibility. As suggested in an earlier post in this thread, I will try with a counterweight and see if it reverses if I make it East heavy when pointing East. It may not be a solution that works for unattended imaging, but at least there will be an answer.