My Starboard drve creeps all the way down from Trailer postion after a few days. I know it's not the rams or lines all is brand new and it worked it's way down with the old Transom assembly and rams. So It's the pump. I know there are up and down valves in the pump. So if it is creeping down what valve is failing in the pump itself, the Up or down.???

I saw the valves in a drawing I'm sure they are easy to replace.???

If your going to have it apart you may as well replace them both.