Hi Rick: I have had experience with Schoenhut's baby grand toy piano. It uses a row of hardened steel rods attached to a frame. The hammers strike each rod creating a tone. To tune (I used an accutuner), raise the pitch of a note by grinding a bit of metal off the end of the rod. To lower the pitch, solder a bit of solder to the end. Schoenhut still has parts for these toys, I used a new set of rods which were woefully out of tune. Mike Kurta
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