My CGEM stopped slewing in RA at a consistent position after I replaced the battery. Resetting the mount to factory settings fixed the problem.
Hope this helps someone.
The problem started after I rebuilt the mount. I replaced the battery while the mount was apart and thought that the battery only kept time, date, and location. When the mount stopped slewing at the same position in RA I was afraid that I had damaged the ring gear. I mucked with the mount for a few evenings before I realized the problem might be in software instead of hardware.