Problem(s) Encountered:

I rotated to zero using the red/blue tape fiducial -- at delta = +75 on the meridian -- and found that the rotator was reading -5 degrees, so the instrument rotator appears to be having an issue.  I wonder if it might be position dependent.  Is there a more precise zeropoint fiducial than the tape?

Solutions:

It may well slip at large angles as it is a friction drive system and roller interface for the encoder. I know it’s demonstrated issues such as this historically, which is why it’s recommended to be near zenith when rotating.