I recently purchased a used Pedersoli Sharps. It's a real honey except for the rear sight. When I received it, the screw on the left side of the slider was very loose and it would not stay up. I tightened the screw and it will stay in place but it is very rough and difficult to move (without a screwdriver). My other military ladder sights have a spring that provides tension, locks the slider in place but allows for rapid readjustment. My Pedersoli does not have a spring (with it). My question is, Is there a missing spring, is this normall?, Poor design? Any thoughts are welcome. Thanks for your consideration, cogitations and opinions.