The player Jay Merrill refers to is identical to my own Hupfeld
Blüthner.  There are very few of these 65/88 Hupfeld Blüthners around
and to my understanding they were made specifically for the UK market
and all known Blüthner upright 65-88 examples (there are less than
half-a-dozen presently known) appear to date to 1913.

The type of stack used in the player is Hupfeld's superbly engineered
pre-WW1 regular Solophonola player masterpiece, nothing more, nothing
less!  Mine also is still playing off original cloth throughout without
any problems.

Underneath the keyboard, the "stuff" referred to on the front of the
exhauster assembly are the two theme regulators for the Solodant
themeing system.

Play and Reroll are all controlled from one lever along with the Tempo.
In the most recent PPG Bulletin ( http://www.playerpianogroup.org.uk/ )
I have written a longish article about player console ergonomics and
I personally reckon the Hupfeld control console of pianos of this era
to be the most ergonomically designed and simplest to operate.

The Tempo lever has three positions: far right is "re-roll", far
left is "Play", and moving the tempo lever from the far left to about
three-quarters-to-the-right takes the player from zero paper speed to
prestissimo.  Pushing it farther to the right disengages the stack but
leaves the roll motor in "forward" and this is the "fast-forward-silent"
mode.  Further pushing to the right pneumatically disengages the
transmission drive and engages reverse, i.e. re-roll.

The tracker bar is not aluminium but what the trade catalogues of the
period refer to as "German Silver".  Tracker bars made from this stuff
were more expensive than brass.  It doesn't tarnish like brass and is
a harder, more durable metal.

One of the videos quoted ( http://www.youtube.com/watch?v=JwKX6R2gXxA )
shows my player a few days after it was delivered to me after sitting
pretty much idle for a few decades.  It had travelled half the length
of the UK and had yet to be tuned!

At http://www.youtube.com/watch?v=keT4kQwT_aA on another piano in the
UK identical to mine, you can see the player in 65-note mode.  The
music I recorded is a piece by Emil von Sauer on a Metronomic roll made
by the UK Imperial label.  Above the tracker bar behind the roll you
can see the tracking roller which, being in this inverted position, is
disengaged though 6-per-inch rolls just don't mistrack on this system.

At http://www.youtube.com/watch?v=Vf4WyXNUCpk in the second video on
this piano, I recorded the 88-note playing mode via an original Hupfeld
1921 dance roll featuring a light number from a Robert Stolz operetta.

Another video, not mine, ( http://www.youtube.com/watch?v=QIPBlkNb15U )
shows a post-WW1 model with a conventional player stack above the
keyboard.  In grand pianos the Blüthner Hupfeld Solophonola is possibly
the finest player grand money can buy, for those who are serious about
their classical Hupfeld hand-played rolls, and indeed all rolls!  See
http://www.youtube.com/user/RollaArtis (36 videos) for what a Hupfeld,
Animatic and SM rolls are truly capable of.

Regards,
Adam Ramet
http://www.undergroundpianola.com/