I have a 85hp force 1989 model # 858f9b serial # 1336. Problem is with the tilt trim. Everything works fine until motor is put in gear with the motor titlted up. Motor will slam down against trim cylider in forward and will tilt all the way up in reverse. When boat is out of water and motor is tilted up I can force motor back down.But to do it I have to put all my 230lbs and my wifes weight combined to do it.So you see it takes a lot of force to push it down.I bought a force manual and did the recomended leakdown tests. Both test passed I even did each one overnite to give it plenty of time.The tests are used to determine which part is bad trim cylider,lift cylider or pump.I can push the motor down manually during each test. The fluid level is full .I ran the motor up and down several times to make sure no air is in system.After all this I still don't know which part is defective.