> 1. Theory:   Someone re-pinned the barrel.

You are exactly correct.  The barrel was repinned with a new tune.
This was done when customers tired of their music and wanted new music.
The barrels are not just logs, they are built up and were very
expensive, so many companies offered to change your tunes from time to
time.  The actual work was probably less expensive than building a new
barrel

D. L. Bullock    Piano World    St. Louis