Symptoms

1. There is transparent, slightly viscous liquid oozing out from the bottom of the printer;
   
2. When clicking TOOLS - EXPOSURE CLEANING, you can observe bubbles on the screen.
   
Before observing the screen, you can place a piece of A4 paper on the screen to prevent light glare.

Diagnostic Steps

1. Turn off the power switch and unplug the power cord;
   
2. Remove the rear casing of the machine;
   
   

   
   

   
   
   
There are wires connected to the rear casing. Be careful when removing it to avoid breaking the wires. After being removed, it can be leaned on the left casing of the printer.


3. After removing the casing, you can see the whole coolant system, please check whether there is any damage at the position marked in the first picture below. 
   
   
   
   
4. If leakage is found at position 1, please see the help page to replace the coolant tank:-- ; If leakage is found at position 2, please refer to the video tutorial to replace the coolant temperature sensor with a new version and add coolant: https://youtu.be/B-IW-wFWSwU; if liquid leaks at position 3, please follow the tutorial to replace the water pump: https://youtu.be/OHdu0IWiaTc.
When replenishing coolant, be sure to use UNIZ brand coolant. Mixing other brands of coolant will contaminate the cooling system to cause foggy issue.
5. After replenishing the coolant, if the bubbles on the screen do not disappear, please refer to the bubble removal tutorial to remove the bubbles.
   

Conclusion