IBM 2104 Model DU3 - Manual (Page 42)

15. Reinstall the switch card assembly:
a. Refer to Figure 19.
b. Insert the switch card assembly into the 2104. Push the assembly in until it
stops.
CAUTION:
As you push the assembly fully home, the lever automatically moves
toward its closed position. Ensure that your fingers do not become
pinched between the lever and the assembly.
Figure 19. Inserting the Switch Card Assembly
26 2104 Model DU3 Installation Guide