I cracked the corner of the top - doesn't hurt a thing, as long as the full cap is intact. If you use the same syringe for each color, be sure to rinse it thoroughly with clean water. No drill needed for this cartridge as the vents are open. Insert the filled injector's needle into the vent hole and then with a slight force, push the needle through the sponge toward the bottom of the compartment. Very slowly inject the ink, raising the needle as you inject, until the injector is empty.
Instructions show the location of each color or test with a toothpick.
TIP - use one hand as shown with the thumb on top of the plunger and a finger on the plunger's stem for control when injecting the ink. Wipe the needle with a tissue and blot any excess ink around the fill hole. Brand names and trademarks are used for descriptive purposes only and remain the property of their respective owners. Their use here does not imply endorsement by or association with the owner companies. All rights reserved.