The piano front has the original makers label
and the winding handle.
The handle on the left side of the piano 
is used to change the tunes.

With the front panels removed 
you can see the main barrel and the hammers.
These are mounted on a pivoting frame that allows the pins to be drawn away from the barrel whilst it is being changed to avoid damage.

The notes are produced by a series of pins.
These are operated by the winding handle on the front of the piano.
This drives the crank - shown here on the left..
Each barrel contains six short tunes. The tunes are selected by the barrel being move left & right.