2nd possibility:

Release switch by turning it 90° and pull it out of the installation opening.
Pull operating plunger out of the switch as far as it will go.
Reinstall the switch. When installing the switch for the first time, it is essential to press it vertically against the bearing surface. It will otherwise not be possible to lock the switch (90° turn), even if great force is exerted.
NOTE: A play-free fit of the switch is no longer ensured after it has been installed and removed several times. The switch must be replaced by a new switch as soon as it perceptibly "wobbles" in its receiver.