IBM Selectric I/O Manual Of Instruction page 35

RELEASE PI N CAM FOLLOWER ARM
FIGURE 69. Shift Mechanism
The upper case armature has a formed end that extends to the
rear and serves as a latching surface (Fig. 70). The lower
case magnet armature is spring loaded to the front against the
formed end of the upper case armature (Fig. 71).
Pivot
Plate~
FIGURE 70. Upper Case Magnet
Armature
Coil
Stop Plate
FIGURE 71. Lower Case Magnet
26. 1