Yamaha GH-1 Grand

[DGPEAKE]

Dear Friends and Fellow Technicians,

I recently serviced a Yamaha GH-1 Grand made in 1978.  A few notes in the
lower mid range tuned very shallow.  The SAT said ok, my ear heard it flat, I
tuned to what my ear should hear, but it sounded shallow.

Does this model have a problem in the stringing scale?  Shoud I re-scale it,
or does Yamaha have a new scale for it?  I do not want to my client to waste
$$$ on rescaling and restringing it if it will not help.  

I am not sure it is voicing or if my ears are going whaky.  Your advice will
be much appreciated.

Sincerely,

Dave Peake, RPT
Portland, OR