Motor will not trim all the way down

[Lantzmtn]

I had to manually lift the motor to move the boat before Hurricane Irene came through VA because my battery was dead. Tried to take it out last weekend and now I can't get the motor to go all the way down. Seems like there is an air lock in it, I can push it all the way down but it springs right back up. I drained some fluid off and it went all the way down. When I replaced the fluid, same problem. Any ideas? It is an 1988 Yamaha 2 stroke 115 on a 18.5 Wahoo center console.

[boats.net]

Try tilting it up all the way, top off fluid and open manual release valve and allow motor to go all the way down on it's own, raise motor back up by hand and top off fluid again, then let it drop down again. Tighten manual release screw and try it.