I just had the shft shaft seal replaced on my 1988 75 horse Mariner. Now I am having the worst time reinstalling the lower unit. The problem is getting the gears to correspond correctly. When I finally get to seat all the way it will ratchet in forward and neutral and turn freely in reverse. I can put it in neutral with pliers no problem and put my throttle in neutral but for the life of me it will not seat all of the way. I must be missing something because I have had the lower unit off in the past and put back together without any problems. But this time the teeth dont seem to be lining up. I know that the drive shaft isnt the problem because as soon as my daughter shifted into forward gear it seated all of the way. Any advice would be much appreciated