Dear friends,  I have a 1931-1938 Haines Brothers Ampico Grand (4' 8")
that contains a "B" drawer with radio knobs.  The piano action is
unlike most actions that are found in late Ampico grands.  The front
of the action is marked "GG Grand Keys" and the sides are marked
"PO 533".  I can supply photos to help identify the action.

Does anyone know what kind of action it is?  Has anyone ever come across
regulation hints for this type of action?  Thanks for the assist!

Best wishes,
Mike Walter