I inherited my father’s 1961 J45. I had some work done to mitigate some water damage, reset the neck, refasten loose braces, tighten the bridge contact, and replace the nut and saddle with bone. It plays and sounds great…except on the low E 12th fret, the note just thumps instead of sustaining. Above and below the 12th fret, it sustains longer the farther away from the 12th. The same note, played on the 5th string 7th fret has the same issue, just not as severe. Tapping on the top by the bridge, the resonant tone seems to be this same pitch. Is this common and what can be done about it?
