Merlin 3070 Service And Maintenance Manual page 206

(ZH802A) ATTENDANT INTERCOM SELECTOR KIT (31642)
Remove back rail by sliding rail to right (Figure 3).
7.
8. Remove front rail by sliding rail to right (Figure 3).
FRONT RAIL
SLIDE
Align the mounting tabs on left side of the Attendant Intercom Selector with slots
9.
on right side of voice terminal base and press down into place (Figure 4).
END CAP
Figure 2
BACK RAIL
SLIDE
Figure 3