Trims down, not up, not solenoid?

[crackerjack]

1999 Mercruiser 3.0 with Alpha 1 Gen 2 outdrive.
Quicksilver 3000 Classic throttle control with thumb switch to trim up or down. Separate switch trims up for trailering.

Trim down works, but not trim up. Trailer switch will trim it back up.
I disassembled the throttle control and cleaned all the switch contacts and replaced both up and down solenoids but the problem remains. It won’t trim up except when using the trailer switch. Suggestions?

 

[muc]

bypass or replace the trailer limit switch

 

[Chris1956]

On one pivot point, where the outdrive pivots for trim, is the trim gauge sender, the other is the trim limit switch. These are open to the water and often fail.