The stepper motor is using a rotary variable resistor for the ecu to work out the position of the cables. Every units hi/lo position will be slightly different hence the amount of adjustment in the cables to be able to set the rc valve accordingly.
As Andy has stated the marks are more directional than fixed points.

I am just putting the final touches together to be able to refurb nsr 250 stepper motors cheaply.... Ill keep you posted!