Re: lower unit assembly help!
OK--I know that little puppy. When yo disassemble, you must remove the four bolts holding on the lower unit. Then, with the gearshift in forward, you must reach in the gap and using a screwdriver or allen wrench--depending upon which screw type it is--remove the screw holding together the shift rods. to reassemble, you must put the gearshift in forward and pull up on the rod in the lower unit to get enough space to reassemble the two shift rods. Mate the ends then insert the screw to clamp them together. Now remember, this is done after the drive shaft and water pump tube are properly located. There will only be about 1/4 to 1/2 inch space in which to work.
Now, when you push up on the lower unit and insert the four bolts, either the gearshift lever will move or the internal rod will move downward.
The end of the lower unit shift rod is screwed into a flat plate with three detents. It rides in a slot in the lower unit and there is a bent metal spring to hold it tight against one wall of the slot. The dog clutch shaft end rides in one of these detents for forward, neutra, or reverse.
If you have opened the lower unit and lost the spring, it will not shift correctly.
If that doesn't help, let us know what you actually did to the lower unit.