IBM 9080-M9S Manual page 480

Figure 412. Installing an adapter in a cassette for the 9080-M9S system
7. Replace the top cover on the cassette.
a) Lower the top cover on the top of the cassette.
b) Slide the top cover in the direction that is shown in the following figure until it latches securely.
474 Power Systems: Removing and replacing parts in the 9080-M9S system