Hi Ross,  I looked at your pictures and it occurred to me that you
really don't need a whole new piece.  You would perhaps even do better
to just splice a new piece in the old one, since most of the original
piece is there.  What you need to do:

1. Select an appropriate piece of wood, preferably about the same age.

2. Cut a V-notch in the leg that is broken; about 1/2" should be
sufficient.

3. Cut the new piece so that it mates the V.  Glue with any strong
glue and clamp.  I wouldn't recommend a screw here -- it would probably
split the wood.

4. Sand it all to smooth and clean, stain it to look like the rest of
the wood and finish it with a coat of lacquer.

I had a similar problem on my Duo-Art roll motor: one of the arms was
broken that drives the wheel.  I didn't have a long enough piece to
cut a V into it, so I just matched it by pressing one alongside the
other and glued it (with a clamp) and it works fine!

Best regards,
Eliyahu Shahar