I had the same problem with my Hyperion 8-24 zoom, completely gummed-up. I managed to get the plastic sleeve off but I couldn't remove the screw. What I did is to get some WD-40 and sprayed it into a plastic cup. I used a fine artist's paintbrush and put a few drops of WD-40 down the side of the screw. After a few minutes, I was able to move the from the 8 to the 12 position. A added a few more drops. Soon, I was able to zoom across the entire range. With the zoom set to 24 and the lens retracted, I brushed a few more drops round the inside of the tube. The lens is now functioning normally, including the click stops. The WD-40 is obviously thinning the grease.