The coupler needs to be centralised so that the ribbon connector doesn't get pulled off at full lock.
I haven't tried it but I would suggest turning the central spindle clockwise in the casing
gently until resistance is felt.
Rotate anticlockwise counting the revolutions until resistance is felt. Turn back clockwise to halfway.
Let us know how many turns you get, it will help people in the future.
And remember the key word is GENTLY!