Dell 2135cn Service Manual page 716

Chapter 3 Removal and Replacement Procedures (RRPs)
Note: Carefully check the correct
orientation of NVM when carrying out
the following job.
3) Attach the NVMs that were removed
from old PWBA CONT AIO on IC sockets
of new PWBA CONT AIO with its notch
aligned with the notch in IC socket.
4) Attach the PWBA CONT AIO to the
printer.
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Version 
2008.02.01