My parking brake on my Mark VIII does not hold, does anyone know how to adjust it?

are you the first own er it might have been disconected

No I am the second owner and it has a true 80000 miles on it and the parking brake has not been disconnected. It does create a drag but does not hold on a hill. I found what looks like an adjustment near the rear end, but when I turn it it keeps springing back becuase of a tension spring. This must be the adjustment, but there is difficulty in turning and mabe there is some trick. Any suggestion would be appreciated.