Dear all,  The only robot organ that I've seen in real life is the
one that is owned by Norman and Mary Kendall.  Strictly speaking,
as far as I know, it's based on a defunct Decap chassis but it plays
very well and it's great fun and I'd love to take it home!  Below
is a link to Norman's site with a few videos as well.

  http://www.normansorgans.co.uk/the_robot_dance_band_organ.html 

Best regards,
Peter Clarke