Adjusting vacuum servo

WARNING: This page is about a different car, the 1998 Volvo C70. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Identifying Vacuum Valves, Stop (Brake) Light Switch, And Vacuum Servo

Courtesy of VOLVO CARS OF NORTH AMERICA.

Ignition off.
Remove soundproofing panel on driver's side.
Turn the adjustment screw by the ball joint so that the link from the vacuum servo is tensioned, but not so much as to move the accelerator pedal (AP).
Reinstall the soundproofing panel.

Check function.