The last few times I have noticed that the engine is trimming all the way down while in storage for a few weeks, as I pull it up for ground/birth clearance before its put away. Any ideas? The manual release valve seems to be frozen, I can't move it. I can't physically move the engine trim by pushinng on it, and the hydrolics move it up and down ok(although slow). Also, does it have a tilt lock of some sort built in? How does this function?