Re: 90 90hp johnson tilt trim manual release valve
Remove the whole tilt & trim unit. Disconnect and pull the wiring from the cowl, turn the release screw, raise the motor manually, set the lock, unbolt the unit from the mounts, drive the pin out of the center ram, push the center ram in, and the whole thing will come up and out. I believe that covers it.
My trim motor had water intrusion due to a failed o-ring. I cleaned and polished the internals, replaced the springs behind the brushes, and replaced the o-ring. I regret not putting a bead of sealer around the outside of the trim motor, for extra insurance.