Sadev discovered that this spring was a bit to weak for some of the gearboxes. As a result the switch can start to oscillate which of course causes hick-ups for the engine.
We received a well documented change notification request, and the change only takes 2 minutes…. if you can reach the switch.
Lesson learned for next time. Make a service hole into the tunnel so you can easily reach the top of the gearbox.
So for us there was no other solution then again removing the gearbox which made us decide to change also the flywheel to a version with a 60-2 teeth. That way we can move the crank sensor to the bell housing as by origin.
It is more reliable to have the sensor over there.