Thought I would add a little more, and I hope I can describe this accurately.....Before I disassembled this, I had two concerns. The sprocket cluster was a bit wobbly, meaning too much play in the ball bearings. I wanted to tighten that up. Also, as long as I had the unit apart, I could clean it up, and apply fresh grease. So removing the wheel from the bicycle, and laying it sprocket side up on my work bench, I noticed the threaded ring that is tightened up against the balls in the ball bearing was loose. I went ahead and loosened it up all the way until the entire sprocket cluster came off. And, of course, all the balls fell out. So this threaded ring is tightened up against two very thin circular shims. These shims allow the threaded ring to be tightened up completely, while still allowing the correct amount of play in the bearings. So, now I have the sprocket cluster off the wheel, that inner threaded ring is loose behind this outer ring...and it is this outer ring that I want to get off with the special tool. This needs to be done so I can re-install the balls easily. I hope this description helps! Again, I sure appreciate your help. Sure would be nice to get this done, so I can hit the trails again!