1996 Johnson 150 Fast Strike Tilt Problem

[sddeneve]

Problem-tilt will not go down in full up position
Frequency-intermittent
Information-will not lower from either tilt/trim location, tilt/trim motor is running, no help when downward pressure applied to motor with switch activated, no problem after manual release valve is used to lower motor no more than 1/8" from tilt cylinder full extend, noted after about 30 minutes following failure, left alone, tilt will lower using switch.

Suggestions appreciated!

[boats.net]

Check for air in fluid.