In the Gulbransen literature, the "Registering" refers to the 88-note,
non-reproducing player mechanism.  In their words, it "registers the
touch", but you have to do it all by yourself with the pedals and levers.

The auto sustain?  Well, you either have it or you don't.  It's a single
pneumatic on tall legs in the bottom left of the piano and lifts the
sustaining pedal rod which has a wooden "donut" around it.  This is
lifted by the tail-arm of the sustaining pedal pneumatic, which by the
way has a wonderful leverage system to help it work responsively and
effortlessly!

The more expensive a Gulbransen model was the more detail it tended to
have (like brass plating instead of nickel plating).  I believe the
"Community" model was the least expensive and the "Whitehouse" model the
most expensive.  Prices (Nationally Priced) and this name/model
designation will be stamped on the upper back of any Gulbransen model.

If your serial number is correct, you more than likely have the late unit
pneumatic stack, which is a breeze to rebuild and makes an incredibly
"snappy" player.  Nice to work on and great to play.  Pianos (with proper
restoration, i.e.. hammers, dampers, strings and usually a bass bridge
apron etc.) are also much better than the prevailing attitude towards
them.  Each one I have worked on (excluding the glued-together beasts)
is a delight.

Robin  Pratt