IBM 9009-22A Manual page 27

Figure 10. Opening the BPM holder lever
e) Unlock the BPM handle (B) by pressing the handle release latch (A) in the direction that is shown,
and pulling out the handle toward you. See the following figure.
Drive backplanes for the 5105-22E, 9008-22L, 9009-22A, 9009-22G, 9223-22H, or 9223-22S 13