Tightening open/close drag on G3 Powerbook lid/display

After years of opening and closing the display/lid on my G3 Powerbook, the lid has loosened on its hinge to the point where the display won't stay upright without leaning it back on something solid behind the computer. Can anyone tell me how I might tighten the hinge, or if it can be tightened at all? I can not find any set screws or other device to tighten the drag on the lid.

thanks for any help,
Richard