My 75 horse Mariner slowly loses pressure when trimmed up. A mechanic told me it was probably a valve that went bad and didnt think that it was a big deal to fix. When I looked at a schematic of the trim assembly it showed a screw on the side with some little o-rings near the tip. The whole thing is called the valve assembly. Is this what he is talking about. He also mentioned that the tip can break off inside of the pump.