Slingfire gearbox locking up

I modded my Slingfire, pretty standard stuff. Just an AR removal. There are pieces that I'm not sure where to put (a small metal bar similar to the one holding the lever in place and what looks like a lock). Here's a link to pictures of the internals and the lock-like part: https://drive.google.com/drive/folders/1-GtLbl0q_jVmZEkzzdhS5w6JRXtdOe3V

Thanks in advance!