Alex, thank you for the reply that would be the 4 items in the middle, longer one on left? Levers used when a key was pressed to open airway? I've seen images of wood ones similar in shape. But these have a narrow slot to slip material in I think. I can't see a wood lever that thin lasting. Would a different material have been used or did these make stencils? Kind of an over kill for that, I would think. The 4 screws could open the 1/8 inch gap and tighten down on material I suppose. I'd like to know enough to actual try it out, some how. After material slipped in was it tapped down and through with a mallet or some press machine? The top edge is not damage, as one would suspect if struck with metal hammer over the years. I believe they made over 100 bandoneons, I saw a posting of one identified as 92.