I used tooth paste on the cups to work them down, and it worked, but took a lot of time. I had to cut the head off a long 2 mm screw and run flanged nuts on it to hold the ball. I then put the screw in a drill and ran it for a couple of minutes. After that I cleaned out the tooth paste and added lithium grease. Now they are very smooth and move freely. I finished my diffs and don't really know how to install the rear plastic inserts for the hinge pin, is it 0* in the front, or the other ? And how are they oriented??? I had to stop there for now.