Craig Smith wrote, "... you should be able to buy some carbon brushes
for another motor and shape them to fit rather easily."

I have cut down larger carbon brushes using a hacksaw and then finish
shaping by rubbing on a flat metal file.  Also, fine sandpaper, emery
cloth, and emery boards all may used to shape brushes, which are of
a very soft and easily worked material.

A larger diameter rat-tail file, or better yet, a drum sander may be
used to shape the concave end of the brush where it contacts the
commutator.  While this step is not required, it will help the brushes
seat more quickly.

What a cool idea about recycling the carbon rod from a C cell battery!
I always have a can of used batteries I'm saving for the recycling
center, so that may be a good source for a carbon rod in a pinch.

Tom Lear
Tujunga, Calif.