this is my first post. i'm from switzerland and my english isn't the best.
i've had the same problem like you, my zipper of my poiak was also broken.
I've lost the small piece on your picture to close the zipper.
The Producer of the zipper is: Lanfranchi Lampo Zippers - metal, moulded plastic and coil zips, pullers, pulls, sliders and tag RFID.
I've wrote them to help out and got the missing piece of the zipper for free (it's the T3). Possibly they can solve...