If the hole appears to be smaller and the baby experiences difficulty drinking, the top is probably clogged. To unclog the teat, roll the tip of the teat between the thumb and forefinger to loosen any build-up. Wash teats using a mild detergent and water after each use, rolling the tip of the teat between fingers during washing will ensure to clean out any leftovers.
If the hole appears to be bigger or shows any other sign of damage or weakness, replace it by a new one. For hygiene reasons, we recommend replacing teats after 3 months.