1991 Force 90 HP Shift linkage

Does the linkage shift arm in the lower unit shift side to side?

No the only movement is up and down.
Pics of the arm?

I must have a shift linkage problem. I replaced the water pump and when I was installing the lower unit back in place, in guiding the lower shift rod into the opening in the upper unit, I noticed it felt loose, and will pull right on up out of place. I can push it back down and feel that it goes into a slot, but it will not "catch" or stay in that "slot" I feel. I have not removed the Gearcase cover or done anything else to inspect the shift rod connection. I don't know how to proceed from here but it looks the shift rod must "lock" into shift arm. the lower unit is in forward gear where I placed it before starting the gear case removal. I tried loading a picture but it is not showing up in this reply.

In the manual it looks like the rod is threaded, and the install instructions is calling this rod the "intermediate rod". I would like to know if I will have to remove the gearcase cover to properly install the rod back and is it right hand threaded, if at all.
Thanks everyone!

IF??? you unthreaded the rod???? Then yes you'll need to partially dismantle the lower.(remove the cover)
Did you undo the slotted screw on the side of the gear housing??? Yes? then the lower needs a complete
dismantle.

Well, I did not unscrew the slotted screw, and I was able to reinstall the middle shift rod and screw it back into the lower shift rod without removing the gear case cover! This is only my second water pump rebuild on this engine. I'm boat second owner. So I have no idea how the middle shift rod got unscrewed, must have just been ready to come undone when I pulled the cotter key and pin out of the connection! The good Lord is watching out! Shifts just fine! Yea!
Thanks

Great!!