What are your trainers and managers doing? I wonder why so many people are asking this question now and how good the manager is. This problem is mainly caused by the incorrect ratio of air to milk. When cleaning, the water is not drained cleanly. Or check that the sealing gasket may not have been installed properly when installing the machine. There should be a very important part on the machine called the exhaust filling plug, which plays a great role. Pay attention to its presence when cleaning and installing. The solution is to strictly follow standard procedures. The appearance of a freezing cylinder will also cause damage to the machine. Shut down the machine first, do not force it, then disassemble the machine, discard the mix, and then install the machine according to normal procedures.