Hi Dale,  The one 'T' connector you referred to in your article sounds
like the connection from the push button "Loud" control in front of the
keys to the Auto-Sustain device in the lower left hand corner of the
unit.

The other 'mystery' connection goes to the 'On-Off' switch in the
spoolbox, in the upper half of the piano.  That switch is in turn
connected to a hole on the tracker bar which senses the auto-sustain
perforation on the music roll.  This configuration allows the user to
activate the sustain manually or (with the 'on-off' switch in the 'on'
position) automatically (with the music roll).

Beckwith players used a variety of player mechanisms in their player
pianos, so you'll have to identify the exact type before any specific
reference materials can be purchased.

I recently wrote an article for the MMD explaining the four major player
mechanisms and how to identify them. The article is at:

    http://mmd.foxtail.com/archives/Digests/199907/1999.07.03.11.html

Musically,

John A. Tuttle