Pressman had a jam up and we get little rips in paper on gripper edge. Figured it was one gripper bar and set each gripper to 65lb. cover thickness (we are running 7pt high bulk.) Ran some 60 lb paper and it was worse. Eliminated all but 3. Removed gripper bar and cleaned with blanket wash. Also laid gripper bar on flat surface on top side of grippers. Looked straight. What should I do next? Are there any mechanics in the Philadelphia area who would be good at solving the problem?