How to secure square grill?

[Emma&Al]

The square grill on my Caravelle seems to be flapping about a bit. At some point a previous owner has secured it with thick black sticky sikaflex type stuff which is now ineffective. I can see it has those large plastic screws which I think you do a half or quarter turn to secure but that doesn't seem to work now.
How were they secured orginally?

Thanks Emma

[Dazco]

They need a proper socket to fit into , they are available from Brickwerks I believe
Ive just looked at Brickwerks and can't find them.
Here they are from heritage
https://vwheritage.mobi/GB/productDetai ... D=49949518" onclick="window.open(this.href);return false;

[Emma&Al]

ah great thank you!!