[ David Snelling wondered if the missing part could have been
 [ a tuned wooden block.

I am mostly amused that someone might expect a _tuned_ wooden block,
but certainly it is the case in most barrel pianos to have a woodblock.

Just try _any_ woodblock -- you will notice that tuning is most likely
not necessary.

greetings by(e) InK - Ingmar Krause
ERlanger drehORGEL-Trio, Familie Krause, erorgelt@erlangen.franken.de