Dell 2135cn Service Manual page 700

Chapter 3 Removal and Replacement Procedures (RRPs)
5) Rotate the STOPPER PIVOT to the left,
secure the STOPPER PIVOT to the
DRIVE ASSY MAIN frame.
Go to the next replacement step:
Replacement 28 KIT DRIVE ASSY PH (PL7.1.99)
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Version 
2008.02.01