Bernard Controls FIRST BC AQ SWITCH 150-1000 Serie Guide De Démarrage page 19

6.2 Opening / Closing position indicator

You do not have to remove the actuator cover to set the indicator.
To open indicator, unscrew black ring of the indicator transparent cap (3)
and remove it.
To close indicator, put back the transparent cap (3) on indicator base and
screw the black ring on the base.

Make sure that the actuator cap is correctly reassembled on its base,
otherwise actuator tightness is not guaranteed anymore.
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