The last types of seats fitted in the Volkswagen Beetle were equipped with an infinitely adjustable backrest, on all models before that the backrest position was limited to a few positions.
The black plastic rotary knob is attached to the metal seat adjustment system.
It often happens that the clamps on the button break and the button can no longer be fixed, so a new button is the only solution.
Useful information from Paruzzi magazine and from our YouTube channel :
Look for more technical articles on the page Paruzzi Magazine