Hi, swiveltung. I am new to the forums, but an old fan of Guild guitars.
I have a problem similar to the one you mentioned here.
Do you have an update?
Which model Songbird is the “hum” problem in?
I have seen 3 different models:
1. 3” (approx.) deep body, thinner but like regular acoustic construction.
2. 2” deep body, one piece back and sides, knobs on side near neck joint
3. 2” deep body, one piece back and sides, knobs on side but on upper bout
My two Songbirds are type 3, both made around 1993. My first one is my main gig guitar I have used since I bought it new. Lots of wear from beach weather. Sounds great, works fine.
My second is in nearly new condition, hardly ever used. That is the one with the “ground buzz or hum” problem.