96 90HP 2 stroke tilt losing pressure

Recently bought a Whaler with a '96 90HP 2 stroke w 350 hours. Tilt/trim seems to function normaly when running. However I left motor tilted-up at the dock and when I returned it was back down at running angle. Repeat tests indicate tilt cylinder is not holding pressure.

Any thoughts / reccomendations?

[boats.net]

Try tilting motor up all the way and continue to trim up for a couple of seconds, repeat in down position. Sometimes if there is debris under one of the valve seats holding pressure on it will free up debris. If that doesn't work then the unit will have to be removed and rebuilt.