The assembly that this piece is in is the tabulator. In your original post, you mentioned that the tab set key wasn't working. I wonder if this is it (either the other end of the tab set or clear keys, which reach up and push the little tabs in the tab rack on the carriage up or down, or the tab finger itself which stops the carriage when it hits one of those tabs). If so, the key and this thing might be part of the same problem. You might want to trace the tab controls from the front to the back and see if any lead to this rogue bit of metal. Once you know if it's connected to one of these, the next step should be clearer.
Typewriter restoration, like old house restoration, seems to be the art of peeling onions.
Unfortunately, my KMM is in storage at the moment so I can't look at it for reference.