I have a 2001 150 merc O/b 2stroke I just removed the lower unit to replace the water pump impellar. Everything went smooth. Until I went to re install the lower unit back into the motor assy. I cant get it to line up i guess. I left it in nuetral and even tryd to put it in forward gear. Still same thing goes up almost all the way than stops about an 1.5 . I tried turning the propellar shaft but it looks like its in nuetral cause it doesnt turn the driv shaft. Please what am I missing here??