My Mercruiser 888 lower unit will raise but not drop. Years ago I removed the reverse interlock which was full of corrosion and there is no limit switch for trim. It has worked fine for years. I work it with an up and a down button with a solenoid for each. Pump has green and blue/white and black ground, nothing more. One hydraulic line is up ( return for down) and one line is down ( return for up). If I press down, pump runs but unit stays up. If I loosen the hydraulic up line(down return line) with a wrench at the pump OR at the pistons the unit settles right down. I thought it was a stuck ball in the pump so I bought a new one. Same problem. Expensive wrong guess. So basically I have a bare bone set up which is two push buttons connected to a solenoid one connected to the up(Blue/ white) and down ( green) wires on the pump. Solenoids work and pump tries. What the heck could it be?
