| Cause | Symptom | Solution | |-------|---------|----------| | Collapsed pipe | Repeated blockages, sinking ground above drain | CCTV survey + dig & replace | | Tree root intrusion | Slow drainage that worsens over weeks | Mechanical root cutter or excavation | | Displaced joint | Rods pass but debris re-catches | Reline or replace section | | Solid object (toy, phone, etc.) | Rods push object but don’t break it | Retrieval claw + camera |