Re: Precise polar alignment of the azimuth axis
Because of gravity, there is always flexure. It's just a matter ofor, if the primary scope rings are lined with felt or other soft material, the primary scope ITSELF could be moving relative to the guide scope.
I replaced the felt in my 130mm APO rings with solid styrene, as seen here: <http://astronomy.mdodd.com/flexure.html#RingLiner>
That page shows seven things I did to vanquish flexure in my system. You can never pay too much attention to tracking down flexure!