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Thanks, Brian and thanks Paul.

Yes, I always do the calibration close to the intersection of the equator and meridian because the apparent motion of stars is greatest there which would mean a good calibration. You'll see it was done at RA =14 hours and DEC=-7.8. Not exactly at the intersection, but pretty close to it!

The first thing I did when I started guiding was turn TVC to 0. However, I entirely neglected to turn on backlash compensation in PHD2 - the results were good enough without it. I assumed I had it set, but never checked! I did watch part of Bruce Waddington's excellent video yesterday and plan to finish it tonight. The first thing I looked for the shape of the RA curve when I ran GA and was happy to see that the PE seemed low.?

Brian - the reason I changed the exposure time lower was because it seemed to help with the amplitude of DEC guiding, but again, I only observed it over a short period of time.??

What I will say is this - when I checked PHD2 this morning, I was pleased to see that the last part of the guiding seemed very stable with an RMS of 0.69" over a fairly extended period of time. I'll follow your recommendations on PPEC and DEC backlash and report. I expect based on this and also Jamie's observations below that DEC backlash compensation will make a significant difference.

Thanks to all for the prompt feedback.