there is a metal disc-type part where the shoulder of the plunger hits, that has broken into pieces. I am looking for a parts/assembly diagram. Or, failing that, a video on how to take this gun apart. I'd like to 1 I have a Maestri 3G electric stapler and have ordered (and received) a replacement plunger. While taking the thing apart, a spring came out, as did a small silver washer or software development uae (or maybe it fell out of the work closet beside where I was working). Also. Order the part that has broken, and 2. Put this back together so that it will function properly