I have a guitar that was just built by a luthier on E-bay. I got a great deal on it and it is a fine instrument with only one issue. The B string (and only the B string) buzzes at the 12th fret position only. If I push down with mega strength it clears up. If I bend this string ever so slightly up or down at the 12th... the note becomes solid. What do I need to do to fix this? Would appreciate your help....Sunny