After a yearlong attempt to get PEC programmed into the AP 900 mount, (queue the Violins), I finally figured out the problem was due to one of the AP CP3's was for an ap900 mount (225 tooth worm) and other CP3 was for a Parallax (360 tooth worm). Using the correct CP3 the PE was reduced from 3.4 arc-secs to 0.72 arc-secs (terminate the Violins). With that success it was time to find the next failure point. M57 Blue - six@120', Green - six @120', Red - three at 120' M16 Blue - eight@60', Green - eight@60', Red - eight@60' An STC-7 with 60' exposures in an f/3.6 system performs well. The mount is aligned within an arc-minute per recent test.
