I have an AP900 CP2 that developed an odd issue today.
I was doing some solar imaging, and all went well for about a half hour. I was composing an image when the mount made a sudden undirected slew at high speed. I shut down the mount and tried restarting from a park position, but it performed that unexpected slew once again.
I studied the behavior and found it repeatable:
1. Power on the mount (it's set to EXT connect by default), go past the EXT connect menu.
2. Enter the command to start from a fresh park position.
3. At this point, the mount will slew west for about a half second at high speed (at least 1200x, despite only being set to slew at 900x or less).
4. Any attempt to slew east will result in another high speed short slew.
The mount is unusable at this point in time, given that any eastward slew results in that high speed westward slew. I didn't try to see if the westward slew will happen no matter which movement command I give.