>  Dark doesn't begin to describe them.

Sheesh, think of all the trouble people go to trying to ebonize wood.

I haven't tried naptha (lighter fluid) but that might not be a bad idea.
Rare book dealers use it to clean off the occasional stain from old 
leather
binding as well as other bindings.  Seems it cleans without damaging 
either
leather or cloth.  Sure works on gummy glues -- better than alcohol in 
my
experience.

I've had good luck using lacquer thinner on a number of tools.  I bought
a beech handled pad saw that had been treated to a layer of ugly green
paint and found that lacquer thinner not only got rid of the paint, but
also the grime that was underneath the paint.  There wasn't that much
grime, but the result was a nice darker golden beech handle.  Not
brand new looking, but clear.  So I've tried it on other tools that
looked like they had been repeatedly fondled by auto mechanics who
never washed their hands.

Mike in Sacto