From the part loading station, down by your right knee there is and access panel. Open it and look for a metal disk on the right side of the gearbox. There is a notch in the disk that needs to line up with the switch.
If it is not there is a shaft sticking out of the other side of the gearbox.
You can turn this shaft (make a socket to fit the end of the shaft) until the notch in the disk lines up with the switch.