All you do to set them in theory is fit the sensor on the shaft, but not screwed down, and a few mm off from being fully pressed on the shaft, rotate it that way it will let you, let it snapo back again, screw down in that position job done, this is ok 99% of the time.
You can check the output but even when as it should be some can still respond from a slight tweak either way, just have a fiddle.
tabetha