five thicknesses are held by a bolt and a nut. Among these thicknesses, one is a sealing rubber. After some time, the rubber has dried up a little and water leaks. What I need is to toghten the nut a bit. But problem starts because when I try to tighten the nut, the bolt moves with it. Although there is plenty length of the thread available to play but I dont' want to use the wrench because when bolt, if moves because I cannot hold tight enough, the thread washes away. Is there a tool to help me out. So that the tool should hold the bolt end strongly and let me handle the nut, in or out as i wish.