| • | Damaged gasket sealing surfaces (1) | 
| • | Worn, scored, or loose bearing races or worn bearing race bores (2) | 
| • | Damaged bolt threads (3) | 
| • | Damaged oil seal bores (4) | 
| • | A loose, damaged, or restricted vent tube (5) | 
| • | Damaged speed sensor bore (6) | 
| • | Porosity | 
| • | Damage to the exterior of the case/housings |