NEC EXP320R Maintenance Manual page 122

Chapter 2 Configuring and Upgrading the System
6. Lower the lock on the side of CPU/IO module to unlock it, and then pull it out.
7. Pull out the CPU/IO module gently and carefully, and place it on a flat and sturdy table.
Avoid the dusty or humid place.
This allows you to access the devices in the CPU/IO module. For more information on how to handle these
devices, see the associated sections.
Express5800/R320e-E4, R320e-M4, R320f-E4, R320f-M4 Maintenance Guide (VMware)
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Lock
The Lock
5. Installing and Replacing Optional Devices