wipe it over with lemon oil & let it sit for a bit. Should soften the gunk up. Then you can use a soft bristled toothbrush soaked in lemon oil to clean the gunk off. Once you're done, wipe all the excess oil off the fretboard

I use a brush, but larger than a tooth brush. Something along the lines of this:
http://www.walmart.com/ip/DQB-Ind.11...BRUSH/38473233
but with loops for me to put my fingers in to get a secure grip.

It may not be ideal for smaller jobs that require precision, like getting under the ends of frets.
But it works real well for large jobs like cleaning an entire fretboard.


Just don't do what I did when I was first starting out --- sos pads will scratch up your board.

fingernail brush will have a "handle" and is small.

Thanks guys, Soft brush and some Dunlop cleaner seemed to get most to all of it off. It's much cleaner now.