John Grant may find the Knabe serial number stamped into the top of
the lyre.  You have to remove the lyre to get to this.  I just took
the lyre off of a Knabe for repair the case number was 7xxx all over
the place but the only serial number was on the lyre stamped in the
wood.  I have found that to be the case for three Knabe grands.  The
one I found yesterday was 1916.

Jim Kelly - Fur Elise Piano Service
Pawleys Island, South Carolina
http://www.furelisepiano.com/