Weird buzzing sound on Guild Fretless

[BassManPatsFan]

Hey guys,
I have a 1969 Guild Starfire fretless that I've owned for a little less than a year and I like it a lot, but it's been having some weird buzzing issue lately. The action is quite low on the bass and all notes sound great except for the Bb on the E string (6th "fret") produces this loud sort of buzzing sound (unamplified). It almost sounds like the string is rattling against the fingerboard in front of or behind where the note is being "fretted". I have tried a few different sets of strings in the past few weeks (TI Flats, GHS Brite Flats, now D'Addario Chromes) and they have all been doing the same thing. I had my bass set up last at the end of January by Jim Mouradian in Cambridge, so do you guys think that it just needs another setup or what? I plan on calling him today or tomorrow to schedule an appointment, but when I do, I know that it'll probably take another couple of weeks before I can bring it into him as he is busy.

Have any of you encountered something like this on a fretless bass before? The fingerboard in this spot looks okay (not lower or higher than the rest) and I've been thinking that maybe the nut is cut too low.

Any opinions would be appreciated.
-Alex


edit: I just called Jim Mouradian and I have an appointment for a setup on August 15th.

[arai]

howed you get on?