Is the center A/C vent on a W124 adustable mechanically?

When I turn the wheel, the flap visible through the grille opening does not seem to open as far as it used to do.

Using a flashlight I noticed that there is a plastic arm going from the wheel to the flap. The arm moves when I turn the wheel and it in turns opens and closes the flap. To the side of the arm there is a screw but i amnot sure whether the screw attaches the arm/wheel to the flap or whether itis in fact an adjustment screw.

Any ideas?

Also, can I remove the front grille of the center A/C (in case I can adjust the flap opening?).

Many thanks.

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Current Benzes

1989 300TE "Alice"
1990 300CE "Sam Spade"
1991 300CE "Beowulf" RIP (06.1991 - 10.10.2007)
1998 E320 "Orson"
2002 C320 Wagon "Molly Fox"

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