IBM SDMC Troubleshooting, Service, And Support page 18

Figure 1. Model 7042-CR6 parts
Notes:
1. Field replaceable units (FRUs) must be serviced only by an authorized service provider.
2. Customer replaceable units (CRUs) can be replaced by the customer. Definitions of tier 1 and tier 2
CRUs for this model SDMC follow:
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Troubleshooting, service, and support using SDMC