Dell 2135cn Service Manual page 723

Chapter 3 Removal and Replacement Procedures (RRPs)
Replacement 42 COVER TOP (PL10.1.4)
1) Mate the boss of the COVER TOP with
the hole of the COVER POLE IN.
2) Mate the two holes of the COVER TOP
with the pegs of the printer by pulling down
the COVER TOP.
3) Secure the rear hook of the COVER
TOP to the printer.
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Version 
2008.03.31