Troubleshooting the fuel door pin not engaging upon locking the car.

I'm searching for the trouble shooting and repair of the fuel door assemby/locking pin/piston on my 2006 W211.

The fuel door does not lock when locking-up the car.

Is there a tutorial on this on PP, or a process to determine what is not working?

Thanks for any help!

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'06 E320 CDI
'17 Corvette Stingray Vert