T4 2014 Graphite Rear Arm Stiffener (2)
The carbon plates are fastened with screws M2.5 with 1.5mm allen head.
Therefore it is extremely important to use a hex screwdriver is in a state of 100%. A hexagon with wear will destroy the screws.
It is also necessary to go with caution to the screws. Not tighten too fast, do not fix sloping!
In order to be absolutely on the safe side, you should precut the thread in the plastic of the wishbone.
On the other hand, it may be that screw heads are round or broken screws.