Howdy all, first off this is a great forum with a ton of information and helpful people. Im a first time poster and am completely stumped with my current situation. Allow me to elaborate. I have a 1969 mercury that runs great, only problem is it was blowing some exhaust from where the lower unit and upper u, it mate. I pulled it apart to inspect and on putting it back together, it now will not shift out of forward. I'm sure I probably was not careful enough and things became misaligned. The lower unit will spin either direction freely, as soon as it is mated to the upper half it refuses to shift out of forward. I have taken it apart probably 20 times and tried different ways of aligning, but still nothing. The shift shaft is rotating just no shifting. Any advise would be so grateful!