The round friction fit dip stick on the top of our large hydraulic tank does not 'lock' in place anymore.<br/><br/>Normally when we rotate the dip stick cap, it squeezes and expands the rubber ring sealing it inside the top port.<br/><br/>But now when we see the screw thread fully tightened and the rubber expanded it no longer expands enough to be tight. The cap stays in place but can...