Hi all,  I am in the process of repairing a Hupfeld Phonola
73/88-note player piano.  The pushrods (pitmans) are of wood,
but on the ends is a threaded metal rod that connects them to
the pneumatics.  These are held in place with leather nuts.  They
were literally rock hard, and I had to remove them, but leather
residue is left behind on the threads so new leather nuts will
not have any grip.

I need to clean the threaded rods, and somebody advised me to do
so with a steel wire brush in a drilling machine.  This actually
works a little too well.  Okay, it removes the rock hard leather,
but it also removes the thread.  Slowing the brush or not pushing
the rod against it that hard doesn't help as it won't remove the
leather.

Is there a way to clean the threaded rods without damaging them?
I feel I can't be the only one with this problem, so I hope for
some help.

Regards,
Niels Berkers,
The Netherlands