Adjusting the parking brake

Remove the rear wheels.
Undo the parking brake lever and push back the disc brake pads of the rear axle until the brake disc can rotate freely.
NOTE: To make the turnbuckle accessible, open the cover of the tray behind the parking brake lever and remove the rubber inlay and also the insert.
Undo the adjustment nuts -arrow- on the turnbuckle until the cables are without pretension.

Fig 1: Removing Adjustment Nuts On Turnbuckle
Courtesy of PORSCHE OF NORTH AMERICA, INC.
With a screwdriver (Fig 2), turn the adjustment device through a wheel bolt threaded hole so that the brake disc can no longer be moved.

Fig 2: Turning Adjustment Device Through A Wheel Bolt Threaded Hole
Courtesy of PORSCHE OF NORTH AMERICA, INC.
Turn back the adjustment fixture through 5 notches again (release approx. 3 notches until the brake disc can be moved freely, then release another 2 notches).
Repeat the procedure on the other wheel.
Pull up the parking brake lever by 2 teeth and adjust the adjustment nut of the turnbuckle until both wheels can be turned manually with difficulty.
Release the parking brake lever and check whether both wheels can be turned freely.