On both the early and late style wiper motors, as the motor stops in the parked position, the arm on the wiper motor output shaft should be in the position pointing straight out to the left side of the car. So let yours stop as it wants to in the 1:30 or whatever position, and look at the arm. If it doesn't point straight to the left, remove the nut and the arm, swing the arm (and wiper) to the correct position and replace the nut. Then enjoy showing your mechanic how he screwed it up.