Re: 68 Evinrude shifter problems
I'll betcha Joe is spot on. When I took my '67 55 apart, I had purchased a solenoid kit to replace what I thought were bad solenoids. Turned out to just be a broken wire, but I decided to throw the new solenoids in anyways. I did notice that he rod that the solenoids engage when they actuate must fit properly into the hole that Joe referred to. I remember that I was just able to close the housing but that it wasn't as tight as when I took it off. So I inspected further and found that I too had missed this hole. You have to use a light touch to feel when the rod drops in there. When it does, the housing will close and seal nicely.
BTW, my lower unit doesn't have another vent plug for that chamber. Is oil even getting in there? Could this create an air lock? Or is it okay to forget about it?
EDIT: You responded before I could submit

Yes, it is good practice to tie those wires with a longer extension of something so that when its time for reassembly, you can just pull the whole lot back through the housing.
I don't know if it was a good thing or a bad thing, but when I dropped my lower unit, I found that someone had installed a two prong plug for easy disconnect of the solenoid wires. That was nice of them, considering I couldn't for the life of me get those wires to pull down through the unit.