XJ900 Helmet/Seat Lock Guts

While I am waiting for other parts from my '83 900, I decided to see if I could figure out why the helmet/seat lock wasn't working. The main reason for the helmet lock is obvious - the hoop that goes through your helmet buckle is completely missing. But aside from that, the seat lock doesn't work either. The key doesn't turn very far before getting stuck and it seems to have no effect on whether or not the seat latch works.

So, I took it apart. You can see where this is going...

Started off fine. I took off the 3 screws on the back and carefully lifted off the plate. Everything stayed in place...until I touched it. Then parts shot in every direction across the room. I found the spring, ball bearing, and slider for the helmet lock latch, but it seems like something is still missing. Or maybe it's not put together right. Or both. I didn't see it long enough before it exploded to know if there was anything else. I thought I might have seen another part fly somewhere, but a search of the garage floor turned up nothing.

Has anybody taken one of these apart? Am I missing parts? (specifically, the circled area seems like something is missing) Does everything else look like it is assembled correctly?

Is it even supposed to lock the seat? Looking at the mechanism I don't see how it possibly could. But the lock body is labeled "helmet" and "seat", so that implies it was intended to.

Any insight appreciated. Thanks.

 

After looking closer at the parts diagram, maybe the helmet loop being non-functional on the seat latch is intentional. There is actually a different part for the helmet lock in the diagram (#19). Maybe they just recycled the seat latch from another model that had an integrated helmet lock but left off the loop. The one I showed above was #12 on the diagram. I don't have a #19 anywhere on the bike, and it is not clear on the diagram what it mounts to, but I do have a bolt that seems to serve no purpose on the left side grab handle (#13, see photo below). Maybe my helmet lock is just missing?