Preserve the failed components
Do not wash away grease, contamination or wear debris before photographs and material samples are collected. Mark component orientation so the load path can be reconstructed.
Read the damage morphology
Fatigue spalling, false brinelling, electric erosion, smearing and adhesive wear have different signatures. A single mark should be compared with the full raceway and rolling-element population.
Trace operating evidence
Review mounting records, alignment, temperature history, vibration trend, lubrication intervals and load changes. A bearing is rarely the root cause merely because it failed.