[ Ref. Allan Day in 161204 MMDigest and
 [ http://www.mmdigest.com/Attachments/16/12/04/161204_053207_IMG_2618.JPG 

Hi Allan, This is a Hicks-type barrel piano, probably made in UK,
though similar instruments were made elsewhere too.

On the left side, just around the corner from the crank handle,
there should be a small knob on a lever that you can lift up and it
will lift the key frame up about a half inch.

Just below the lever there should be a vertical brass knife that
engages in a groove cut in a knob that is attached to the barrel
through a hole in the casework.  There should be several such grooves,
each for a different tune pinned on the barrel.

If you raise this knife vertically and hold it there, the barrel
should slide out from the right side of the case, where there is a
removable round board for the purpose.

Good luck, and don't expect it to stay in tune for long.  It should
be tuned a couple of tones flat of standard concert pitch.

David Evans - Editor, Mechanical Music World, The journal of the AMBC
Revelstoke, British Columbia, Canada