Vauxhall CORSA Owner's Manual page 187

Otherwise, the coupling ball bar must
be tensioned before it is inserted into
the coupling housing:
● Place the key in the lock and
unlock the coupling ball bar.
● Push the rotary knob onto the
coupling ball bar and rotate right
while pressed down until it
engages. The key remains in the
lock.
Inserting the coupling ball bar
Insert the tensioned coupling ball bar
in the opening and push firmly
upwards until it audibly engages.
The rotary knob snaps back into its
original position resting against the
coupling ball bar without a gap.
9 Warning
Do not touch rotary knob during
insertion.
Driving and operating
Green marking on the rotary knob is
visible.
Lock coupling ball bar and remove
key.
185