This manual is for refilling NON-OEM Cartridge.
1. Check if the plugs are installed correctly: there are two plugs for each cartridge. A clear plug seals air vent hole (marked "air" on the cartridge). A colored L-shape plug seals refill hole. As an example, the magenta cartridge's plugs need to bet switched.
2. Remove both plugs
3. Fill up ink through refill hole.
4. Put refill plugs back and leave air vent hole open. Air vent needs to be open during printer operation. Insert cartridge into the printer.