1. Put the cartridge on some paper towels in an area you can tolerate a spill
2. Peel back the top lable.
3. Fill the syringe with 5ml. of black ink
4. Very S-L-O-W-L-Y inject ink into the hole nearest to the copper strip ( the other 4 holes are just an empty chamber).
Clean the syringe and needle thoroughly with water, for future use or before filling with the next color ink.
5. When finished, replace the top lable or peel it off (it make no difference in the printing)
6. let the cartridge set for at least 30 mins. to depressurize it.
7. replace the and run 1-3 cleaning cycles as per printer instructions or print a solid black box. if necessary, leave cartridge in printer for up to 8 hours.
The cartridge will print just like a new one. Even though the cartridge prints good, the ink level gaug will not read full after a refill.
Note: You will also notice that this cartridge didn't take much ink. HP walled up 2/3 of the cartridge so only 1/3 has a sponge with ink and the other 2/3 is just air space. I guess they didn't want to give you too much ink so you'll buy more cartridges.