Dell PowerVault TL4000 - Manual (Page 207)

3. To manually release the magazines, push the end of a straightened paper clip
into the access hole for each magazine at the back of the library. While holding
the paper clip, have a second person pull the magazine out of the front of the
unit. DO NOT push the paper clip in more than 1/2 inch.
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Figure 9-2. Access holes for the right magazine
Chapter 9. Service Procedures 9-3