It may be caused by the following reasons:
1. Check the suction cup for leaks.
2. Suction cup pressure is not enough, look at the vacuum gauge, the pressure is above 0.08.
3. Check whether the storage cylinder is blocked, whether there is any gas, and whether it is blocked.
4. Is the cylinder stuck or not in place?
5. Check if there is water in the inlet of the vacuum pump and if there is water in the outlet.
6. Whether the vacuum pump is running.
