I have an OLD unit I bought with my 600Jr 50 plus years ago. I kept it because when I had problems with my 9000's depriming station it was easier at times to just grab this tool and go on. I took it apart a while because it was running rough and I wanted to see if there was perhaps any rust build-up that could be hampering operation. When I put it back together and tried it the mouths of each shell would split or bend. There are only three rings to adjust or change around. All are 2 3/4 in. hulls. What the heck am I doing wrong?