Rear diff lock operation on a 2003 Mitsubishi K74 L200.

When I screw in the diff lock detection switch fully on the rear axle on my 2003 MK III K74 L200 it jams the diff lock on. When engaging diff lock using the air pump, the axle switch must be PULLED OUT (not pushed) to close the switch. When you screw the switch in fully it pushes on the actuator and engages the diff lock without the air pump being activated. I'm completely stymied by this as it looks as if I have to dismantle the axle to get the switch to work.
I have discovered that the diff lock detection switch CANNOT be installed without taking the whole diff and axle apart - that is the half-shafts and diff housing. Then you have to loosen up the the four bolts holding the diff crown wheel assembly and pull it out by 5mm. Then fully screw in the diff lock detection switch. The 'mushroom' is then located precisely behind the lip of the actuator. The diff lock switch operates correctly when the diff lock air pressure pump is activated. I am pretty gobsmacked about this to be honest and it looks like the switch is a factory fit. MY ADVICE WOULD BE TO NEVER UNSCREW THE DIFF LOCK DETECTION SWITCH! You can see its operation in the attached video The tone is when the switch is pulled closed. Good luck!