I am in the process of restoring a 30-note Piano Melodico which was in
very bad condition.  The forte-piano control is totally missing.  The
only indication is on the case: there is a slot, obviously there was a
lever going through, controlling forte-piano, because the slot is
marked on its left side "P" (piano) and on its right side "F" (forte).

I have a also a 48-note Piano Melodico; it has a very tricky and well-
functioning forte-piano control, but this is totally different compared
to what could have been within the 30-notes version.

Does anybody know how the original construction for the 30-notes Piano
Melodico looks and how it works?  Could you provide a digital picture
or a principal drawing of the mechanism?

Would be happy for your help!

Christian Greinacher