The lug is most assuredly loose as well. Spot repair is sometimes possible. I did one for a board member last year and it held up fine. The full job is a bunch of work/money but it is sometimes required.
Correct diagnosis. PM sent.
That was my guess as well when I saw the picture but one thing that I do know...and I have it from a good source...is that many of those production guns even though soft soldered were actually hot blued.
I had an early Piotti in here that suffered from that same ailment.
all best
CJ
