The Aeolian marking machinery sounds very similar to something devised
by the Standard Music Roll Company (inventor George Howlett Davis).
If you go to my web site at http://website.lineone.net/~agr/index2.html
then go to Music Rolls / Brand info / Electra, you will see a patent
picture there (US patent 747858) dating back to 1902 showing just such
an apparatus as Julian Dyer is describing.

As a side issue you can see that the ink marking pen is actually
a ball-point pen -- years before the ball-point pen really became
a commercial success.  The first patent shows their first electrical
recording and perforating device dating back as far as 1896.  The
Aeolian Pianola was still in diapers in 1896!  If you go the US
patent site and type in the numbers you can read the full text.

I am quite sure the 1896 design was perfectly operable on the
description given and would have given a good result.

Adam Ramet