There are a couple of Mach2 threads on Cloudy Nights.

Last night, someone posted a couple of sample images here:  https://www.cloudynights.com/topic/694300-mach2-waiting-list/?p=10752413

I would be interested in understanding what's happening with the image that shows the mount transcribing little loops while tracking.  The author of the post says that changing the counterweight configuration to use higher weight, but farther down the shaft, corrected the problem.  The author suggests that it's taking the encoders some time to correct tracking errors, but my experience with my AP1600AE suggests that the encoders are so fast, that it would be very hard to catch the corrections in an image like that.

Any ideas?