Caused by countercurrent flow of milk for the following reasons
1. The position of the sucking milk is not correct, or the cup that may suck the milk is right.
2. There was a countercurrent flow of milk before, but it was not cleaned in time, resulting in motor blockage.
3, the loss of accessories is not installed, for example, whether the cover is deformed, whether the piston is not cleaned in time, whether the small white film is cracked, whether the hose is not tight, and so on.
4, it is recommended to clean and perfect, pay attention to the posture of sucking milk, pay attention to the contact of accessories before use every day.