Seals
1. Fluid level/pressure is too high.2. Plugged vent or drain-back holes.
3. Damaged seal bore (scratched, burred or nicked).
4. Damaged or worn seal.
5. Improper installation.
6. Cracks in component.
7. Manual or output shaft surface scratched, nicked or damaged.
8. Loose or worn bearing causing excess seal wear.