The oil drip is located at the torque tube retainer. There is a rubber oil seal sandwiched between two O-ring washers inside the screw on retainer. The reason why they start to leak, is because the rubber oil seal gets hard and looses its sponginess and it can't bulge any longer. The screw on retainer cap loosens on the threads because there is no longer any back pressure coming from the rubber oil seal. And the rubber oil seal no longer bulges creating a oil seal at the front end of the torque tube.
