Switch M1 (ID=24068)
The Yellow Toggle Switch
at the square marked
M1
reversez:
the
western
Two-Way Arrow
in square
F7
.
the
lower set of
Two-Way Arrowz
in square
N13
.
the western Two-Way Arrow 
in square F7.
the lower set of Two-Way Arrowz 
in square N13.
at the square marked M1 reversez: