My sp220 is also a 2012. On mine you have to access the motor by removing the kickplate along the dinette. Removing the cushion then the two screws at the corners. The entire kickplate can then be slip up and out of the way to access the slide motor. My manual also shows the supposed drill location, however that is not actually the case.
The steel lug with the cotter pin through it is the actual connection point for manual operation.
It may not be identical to yours, but if you have had no luck finding the exterior hole, then more than likely you will need access to the actual drive motor.