I think the motor only rotates in one direction, coming to rest at one particular point of its 360 degree rotation. The pivots of the wiper "transmission" or whatever its called cause the blades to reverse direction. At the extremes of the side to side motion, the motor is 180 degrees apart in rotation, so I think if you just move the arm that is on the splined peg coming out of the motor you can affect where they park. A 90 degree change would put them right in the middle. The way I understand them to work, the only way you can make them go off the windshield is to rotate each arm on its splined pivot point. I could be wrong.