I have a 1979 55hp Evinrude with hydraulic Tilt N Trim. I have replaced the O rings inside the cylinders and replaced the hoses, fluid, top caps, and fittings. When I try them out with both hooked up they work fine going up, but when they start going down they get stuck and won't move at all. I pushed on the motor to see if I could help it along but it is hard as a rock. I disconnected the one on the left(farside) and the other one goes up and down fine. The farside one is stuck. I took it apart again to see why it gets stuck but I didn't see any reason that it could. Now I have taken the whole thing apart and still can't see why it gets stuck. I honed out the walls of the cylinder just a little to see if it helps but it didn't. I think it is the internal part of the cylinder but have no idea what it could be. Any help will be greatly appreciated as I have spent 3 whole days on this thing!! 
<br /><br />P.S. I can give you any info you need.
<br /><br />P.S. I can give you any info you need.