Re: Tilt problems
textbook symptoms of a valve body that needs rebuilding or replacing. It costs about same $$ either way.
The new valve bodies are of lower quality and durability but have undamaged threads and ship immediately. The rebuilds will run better and last longer but you have to wait while it gets rebuilt. Check iboats, ebay, amazon, google, etc.
While you have the pump assembly off your boat, go ahead and put new seals on the electric trim motor. These motors will last 100 years or until water gets past the seals - which ever comes first. The seals usually start cracking and failing around 20 years. If you put in new seals before any rust starts then the motor will last almost forever. If there is rust on the sealing face then it must be fixed and painted before reassembling. The Mercury Part numbers you need are (1 of) 820549 and (2 of) 8992.