1. Dell A720 Ink Cartridge Refill Instructions
2. If refilling the color black ink cartridge enlarge the hole on top of the cap with the drill provided.
3. If you are refilling the color ink cartridge, the cap must be removed first. Either hold the cap in a vice and snap off, or carefully lever off the cap with a penknife.
4. Assemble the syringe and needle, pierce the bottle seal and fill with the correct color ink
5. Insert the needle down into the fill hole, if filling with color ink ensure that you put the needle into the correct color chamber.
6. Slowly inject the ink. During filling you may need to blot the printhead with a tissue.
7. When the color ink cartridge is full ink appears at the fill hole, draw back the syringe plunger slightly until the ink disappears. Clean the syringe and needle thoroughly with water before filling with the next color ink.
8. The color black ink cartridge holds approximately 20ml of ink. Do not fill with more than this amount.
9. After refilling refit the lid. The best way to secure the lid is to stick tape from one side over the top and down the other side.

10.  Note do not use a sealing plug with this cartridge.

11.  Install the cartridge and run the cleaning cycle on the printer.

12.  Clean the syringe and needle with water for future use.

Source: refillinkcartridges.co.uk