Michael Woolf seeks advice on Piano Melodico restoration.
I suggest he contact either Franco Severi in Italy, who has
a comprehensive collection of these and operates the Piano
Melodico web site http://www.pianomelodico.com/english/main.htm
or Christian Greinacher who has written in the German and GB
journals about them and, I believe, restored one or more :

  Franco Severi <feedback@pianomelodico.com.geentroep>
  Christian Greinacher <c.greinacher@t-online.de.geentroep>
  [delete ".geentroep" to reply]

John Farmer, UK