Vintage Medical Device CAMBRIDGE STETHOGRAPH 1932 Measuring Heartbeats Not Quack

Description

Vintage Medical Device: CAMBRIDGE STETHOGRAPH for Measuring Heartbeats
Not a quack medical device!
This device is used to measure a patient's heartbeats and print them out as a graph on a roll of paper.  A small window to the right of the paper takeup spool is supposed to flash with each heartbeat.  It does something else, but I'm unsure of what it's supposed to be.
The stethograph has several patent numbers on its patent plate, indicating that it uses several different devices inside to make up the unit.  The final patent number, 2099938, refers to the "Electrostethograph," dated 1932, which is basically this device.  The patent description gives the best, although convoluted, description of what this device actually does.
It powers on by turning the "Volume" knob clockwise.  When the "camera" button is pressed, the motor inside runs.  But the belt is broken so there is no functionality.
The paper spool box
on the left side
is removable, as well as the round paper takeup spool box on the right.
The bottom right corner of the paper spool box broke as I was pushing it back in, so I superglued it back together.  The repair is holding, but care must be taken when pushing the spool box back on.
The unit is in a very nice wood box, which is in good clean condition and minor wear.
The box measures 13 1/4" x 8" x 10 1/2", not including the height of the handle on top.
There is a small sticker on the bottom front of the case that says "1956."  It is unknown what the sticker refers to, maybe the date of a repair, or, well, I don't know.
It weighs a whopping 23 pounds!