If pictures exist somewhere, it would definitely help.  Try to remember what all you did to remove this carriage. I googled a picture of this machine, and what it looks like is that you would have had to remove the right hand platen knob with the inner rod attached, so it must have been unbolted from the side of the platen.  Pull the paper release forward carefully, not letting it snap back, lay the platen back inside the machine.  You may want to push a little on the left, but not too hard, to get the variable line spacer mechanism back together, and lay it down on the right side.  Insert the rod that holds that side on.  If the right hand knob is still attached to the rod, then snug it up and tighten the bolt on the side of the platen.  If not, attach the knob onto this rod as far as it will go and then install it into the platen.  I hope this helps.  Good luck!!