I've tried to install a pre-owned PTT(04381350) onto my 1996 Johnson 50hp 2-stroke. Thought I was getting there, working O.K. on the bench, but won't raise the engine when on the boat. I have decided to either buy another unit, or look for a rebuild service in the U.K. Anybody know engineers who tackle this in the U.K.? As for buying a replacement, must it be exactly the same model, or are there others that would fit?