The most common leak over time is the compression seal on the ball to torque tube. It must slide and often the torque tube is dirty or rough at the contact area. With the shims and no sealer the ball can be taken apart(most of the time) with out damage. then the trunnion removed. Drop the torque tube(I use a floor jack to control and lift the tube). Pull the seal compression joint apart, look for any distortion to the seal(it is just cork). Slide the ball off, clean the tube and look for sharp spots that can cut the cork. Reassemble with a light coat of gear oil(on the tube. Snug it all back and keep the compression joint tight( I check mine in the spring and the fall, it is always a little loose). That should help. Channel lock pliers work and a pig pipe wrench will too. Just don't crush the Knurled part and distort it.
