The teat hole and the ventilation valve (vent) on the teat flange may be clogged with milk residues. When these parts are blocked, milk doesn’t flow smoothly and may lead to teat collapse. To prevent this, ensure the teat hole and vent remain clear. When washing the teat with detergent, gently use your fingers to clean the teat hole and ventilation valve. Be cautious not to pull or wash the ventilation valve too vigorously to avoid splitting, which can cause leaks.