where else to look?

[Phil Bondi]

Hi all. 

I am in search of a serial# for a S&S. It's not in any of the usual places 
like plate, key frame, key slip. There is an inkstamp on 2 bass keys..the 
numbers match. Could this be the serial#? If true, this makes the piano a 
1920's vintage instead of a 1950's, which is all the information the client 
has of its origin. There are case part markings everywhere, and they are 
engraved.. 

Any help is appreciated. 

 - Phil Bondi