What am I doing wrong? my "52 spur gear 4 speed doesn't want to go back together. When I sit the tower down, line up the forks to the grooves , the tower sits about 3/8" high. When it slides left or right it sits down on the casting, but it is way out of alignment. What am I doing wrong? This is a used transmission without a shifter so I don't know what gear the tower was left in. Is there a way to tell?