[ Ref. 241202 MMD and subsequent ]

Thanks to all who responded to my query. The comments by Julian Dyer
[241215 MMD] and Mike Boyd [241222 MMD] are of value to owners of
English and Gotha instruments. Other answers simply quoted the Piano
Atlas. My Steck was made in USA, with serial number 69257, for which
the Piano Atlas indicates a build date around 1923.

I have found some drawing copies I received when I visited the late
Harvey Roehl, around 1973. He showed me a large stack of blueprints
and explained that "when the factory closed a friend went around and
collected from the work benches the drawings that had been used for
production of parts." These blueprints were later passed on to Harvey.

In 1973 I owned a "late-style" Steck Duo-Art grand. By coincidence it
has come back to me and this piano is the subject of my dating query.

Harvey tried to photocopy some blueprints of particular interest to me
at the time, including the manufacturing drawing of the miniature brass
switches (Duo-Art on-off; Repeat on-off; Normal-Soft). It was difficult
to copy the drawing with blue background and white lines but I can read
most of the title block. It reads:

The Aeolian Company New York
Pianola Factory Garwood NJ
Assembly and Details of Triple Cut Off Block #8556
R.S.H. Aug 30, 1928 Drawing Number C.B.249

There are some smaller date figures with no explanation visible:

8-30-28
12-4-28
1-10-29

Typical drawing practice (at least in Australia) would suggest that
these dates are, respectively, drawn, checked, approved.

I consider it reasonable to conclude that pianos with these all-brass
switches were built in 1929 or later up to the closure date of the
Garwood plant. A few pianos might be subsequent usage of left-over
spare parts.

In the same parcel of drawings were the manufacturing drawings for the
manual controls for Accompaniment and Theme:

Assembly and Details
Manual Control Expression #8398

Harold Ball
Melbourne, Australia