[GreenKeys] Identifying pulling vs. holding selectors

[Jim Haynes]

On Model 14 and 15, the pulling magnet selector has cylindrical coils
and they are usually black.  The selector armature has rounded ends to
more or less match up with the cylindrical pole pieces of the coils.
The holding magnet selector has more nearly rectangular coils, usually
wrapped in greenish material.  The selector armature is more nearly
rectangular shaped.

Then another way to tell the difference is just to turn the motor by
hand with the line open.  A pulling magnet selector will just sit there
with the armature in the spacing position.  A holding magnet selector
will have the armature pushed up into the marking position by a cam
at each signal pulse time.  So it will wiggle the armature when the
motor is turned.

jhhaynes at earthlink dot net