The juice tray is not installed in place. The juice collecting tray is used to collect and guide juice. If it is not installed, the juice cannot be collected and directed to the correct position. The red light will always flash, so the juicer will not rotate when the machine detects that the juice collecting tray is not installed. Failure to install the upper cover in place may also cause the machine to not work. The above problems can be solved by simply installing the juice collecting tray or upper cover in place.