The springs for the tracker "ears" in the Aeolian can be made out
of very light-weight piano wire.  You can find it at hobby shops in
short pieces.

On an upright, if the tracker ears face the right way, you can get
by without any springs at all.  I forget which way up works.  The
center of gravity is such that it closes by itself in one orientation.
Aeolian mounted them both ways.  I'm don't know if one way came later
and was determined to be better.

Without the springs there is less damage to the paper on rewind.
The ears just fly out of the way.

Spencer Chase