The rolls should never drop unless thereis a problem with the clamp as far as l know l would check the hyd pressure to the clamp most manufacturers have a Max pressure that goes to the clamp also there is on most clamps holding valves in all cylinders if a line goes it will not open the clamp next it is possible that the packing are going bad and bypassing also check the wear pads pins and the gripes they could wear out and cause the roll to drop l also have seen that the bushing in the ends of the cylinders to the pins wear and when squeeze in does not hold correctly. good luck