In discussions with Don Rivera, Airflow Performance, he mentioned that a side effect of installing the FM-200 in a horizontal fashion (instead of the standard vertical orientation) is that the mixture control rotates the wrong direction.
Don will change the direction of rotation for free, but I do have to send the FM-200 back to him. So I removed it from the engine, boxed it up, and will send it off tomorrow. (Actually, Janice will drop it off tomorrow.) I can't ask for better service from Airflow.
Janice also assisted me with changing one of the light bulbs in the hangar this evening.