Hello typers -

I've just acquired an Empire typewriter;



It's a cool machine, but it has issues. First, it's got a "noiseless" style thrust mechanism, which on many of the keys has come undone:



This is easy enough to understand, though probably hard to fix.
What has me stumped is the fact that none of the keys will go down, thus none of the slugs will push forward into the platen. It appears that their movement is being prevented by a piece on the bottom of the machine. Here's the bottom:



And here's a closer photo, with the tip of the pencil resting on the piece of metal (the thick wire like thingy, shaped like an elongated oval:



This piece is positioned so that when a key is pressed, the arm presses down onto it and it prevents anything from moving. Is this a lock of some kind? I've gone over the whole machine and can't find any way to move it. Is it supposed to stop the bottoms of the arms from pushing down so that some other part pushes forward into the platen? I'm stumped. If there are any Empire experts out there, here's your chance to shine. Thanks!