A lot of wolf notes are quite frequency specific if they are created by the top. These are easier to track down and are sometimes only seasonal. They commonly occur at only one or two places on the fret board. There are magnetically mounted wolf-note modulator devices made for cellos to deal with these type of wolf notes, and I have seen these used for carved spruce top archtops. They go in through an F-hole and are retained and moved by a magnet outside on the top. They do the job of Blu-Tack but better since they don't actually dampen the top but modulate its vibration.
The Krentz Modulator changes, rather than absorbing vibrations from the top of the cello. As a result, there is no depreciation in sound quality. Rather, the device actually increases the efficiency of the instrument, allowing the musician to subtly control important aspects of the instrument’s...
krentzstringworks.com
Blu-Tack has been tried on the top, back and sides but with no effect except mildly dampening volume.
Some wolf-notes can be controlled/mitigated by head stock weights. Weight has been clamped to the head stock temporarily. No effect.
Some wolf tones require neck shaving to reduce the mass of the neck. This has not been done.
I have tried a wide variety of strings. Some are better than others (Savrez wound) but none are acceptable.
On and on.
I have been through all this will the best of the luthiers I went to see.
The guitar problem here is more complex. There are false overtones all over the map. No obvious/easy solution, only expensive trial and error with no guarantees.. The verdict was hang it on the wall-it's pretty.
If I tune it down to C or C# the problem is greatly reduced (D isn't low enough), but this low tuning introduces other problems. B might be even better but the guitar is too small to be a good baritone.