Troublesome Spacebar: 1937 Royal Portable Typewriter

With prompt advice from Nick Bodemer and Richard Polt, I was able to get the platen out of this 1937 Royal portable, so I could investigate possible corrosion on the feed roller plate. The rod had refused to move more than a few inches. Nick suggested lots of lubrication and some firm toggling, which eventually worked and allowed me to pull the rod out from the right side (with a gentle tap of a hammer, as put forward by Richard). 

Now, however, I am stumped by another problem. I noticed the spacebar was a little too far back, almost under the front bank of keys, and at a slight angle. It was nonetheless working fine.
There are no bends in the arms of the spacebar, so the cause of the angle had to be elsewhere. Sure enough, underneath the machine, the rod on to which the arms attach is at a very pronounced angle. One end of the rod has come away from its slot and is wobbling about freely, back and forward - and in doing so disrupting the movement of the ribbon colour switch and the shift key and shift lock.

This photo shows the angle of the spacebar

Easily fixed, or so I thought. Once the rod was slotted back into place, it lined up properly, as did the spacebar. But the spacebar just refused to budge. (Yes, the tabs under the spacebar are under the front lip, so that's not what's stopping the spacebar moving.) I suspect now that a previous owner might have pulled the rod out from its slot, for this very reason. There must be something preventing the rod turning in its slots and the arms moving up and down, something which I cannot spot. As I said, the spacebar works OK without the rod being properly attached, but it moves all over the place and interferes with the shift mechanism. I assumed the rod and its arms would simply pivot once it was slotted in, but it doesn't.
Any thoughts? Am I missing something?