The repairer removed the pickup and restrung the guitar. The buzzing is gone and the sound is superb -- big, dark and rich, with excellent sustain. If this guitar were a beer, it would be a Guinness. (My Washburn dreadnought would be an IPA.) I have it on trial, and I'm pretty sure I will buy it. The price is quite low.
There is a hole in the bottom where the pickup plug was removed. I'll need to get this repaired. The repairer at the studio doesn't do this kind of woodwork. She suggested some makeshift options, but for this quality instrument, I'm going to want it done properly. So I'll have to look around. If I can't find a reliable luthier, I do have a guy who repairs antique furniture and has done great work for me.
2016 Cordoba C10; cedar top, rosewood sides & back, mahogany neck
2011 Washburn WD35S; spruce top, tamo ash sides & back, mahogany neck