I am experiencing problems with the p/trim system (conventional) on a 1990 Johnson 140hp V4 looper. After having done a full repair on the engine we mounted the p/t unit on its base and powered the unit 'til the tilt piston was in the proper position. When we powered the unit down the trim pistons were the first to retract (uneven), after they were fully seated the tilt piston started to lower but all of the sudden it went down as if no pressure. Then it wouldn't come up. Mechanic checked for air in the system, worked the manual release valve and replenished the unit but did the same thing. We took the unit to a shop, replaced seals, o-rings and replenished the hydraulic reservoir. The mechanic powered the unit and operated well up and down. We installed the unit back and did the same thing as before. After three more attempts and a new electrical motor installed we decided to quit. The fact that the trim pistons are retracting first when the tilt piston is extended makes me think that something is not working properly or is it? Any suggestions?