This is the hydraulic trim and tilt unit for a 90 hp Honda outboard. The unit did not work, so I checked the resistence on the electrical leads and found that it was an open circuit (infinate resistance). The most likely cause of this is stuck or worn brushes in the motor. In this photo the motor has been removed and is laying on the work bench, the red stuff is hydraulic fluid where the motor mounts.
When I took the motor apart there was a bit of rust and corossion inside. The brushes appeared to be OK, but one of the springs had rusted away.
This motor is built with an internal overheat protection. It is hard to see with all the rust, but there is two round electrical contacts mounted on a bimetal spring. If the motor overheats the spring will open the contacts and stop the motor.
The contacts did not work anymore, so I soldered a jumper wire across them. There will no longer be an over heat control on the motor, but I think that it is unlikely to be needed in our cold climate. I reinstalled this part and replaced the spring in the brush holder and the motor runs great now.