I've got a problem that I figure would best be answered here. When I bought my Warwick Thumb BO, the previous owner hadn't taken very good care of the fretboard. The frets desperately needed cleaning. They were covered in buildup and rust. I figured that the best way to clean bell-brass frets is with a brass cleaner. I carefully wiped each fret down with a small amount of brass cleaner on a cloth diaper. Problem solved, shiny frets. New Problem, brass cleaner stuck in the grain of my beautiful dark Wenge fretboard Lemon oil doesn't do a thing, (I didn't think it would, but hey, I'm retarded enough to get brass cleaner stuck in the grain.) Any suggestions?