Comes apart very easily, under the dust cover
http://diverse.4mg.com/sankyo_clock.jpg
3 nuts to release the winder section, leaving the standard looking
escapement section in place.
^ marks the final brass cog of the escapement and is the balance wheel
adjustment arm.
Not the first cog,A that is breaking up but B. This is coaxial to C, but
separate , that engages with the ^ cog. The spring,shown off to the
side, should be in the section between B and C.
D and E are the 2 cams that flip the 2 part single switch S for the
motor drive, another torsion spring coaxial to D and E.
As the motor drive is worm and so locks the drive train, and is the same
cog as advances the cyclometer dial by 1 minute per turn, I've changed
my opinion as to overal function.
The cams switch , S, must switch the motor on once per minute, one
revolution of the E cam and the D cam perhaps relate to the duration of
motor drive. So motor advances the dial round and also rewinds the
spring 1/6 th of a turn of cog C that has 6 fancy shaped spigots that
must rotate the downwards nib showing to the right of cam E? So why such
a long , multi-turn main spring, if only winding/unwinding 1/6 turn each
time frame of 1 minute?
The motor worm engages with A. That section raised off the tray that I
use for working on such mechanisms because the shaft of A protrudes out
of this section, to the cog that drives the minute advancing cog and
pawl in the display section of the clock.