Allied Telesis AT-SBx81CFC960 - Manual (Page 257)

SwitchBlade x8106 Chassis Switch and AT-SBx81CFC960 Card Installation Guide
Section II: Installing the Chassis 257
Figure 173. Installing a New AT-SBxFAN06 Fan Module
2. When you feel the fan module make contact with the connector on the
backplane, gently push on the top and bottom of the faceplate to seat
the module on the connector. Refer to Figure 174 on page 258.