How to Reset an HP21 Ink Cartridge (7 Steps)

1. Open the lid of your HP printer and remove the HP 21 cartridge by pushing up the clasp that holds it down.
2. Put a small piece of tape over the top dot in second 'line' from the left on the cartridge.
3. Reinsert the cartridge into the printer and wait for it to print a test page or perform a mechanical alignment, which lasts about 30 seconds.
4. Remove the HP 21 cartridge again, and put another piece of tape over the top dot in the fifth 'line' from the left.
5. Reinsert the cartridge into the printer and wait for it to print a test page or perform a mechanical alignment.
6. Remove the HP 21 cartridge again. Pull off the pieces of tape and make sure the contacts are clean, with no glue residue.
7. Put the cartridge into the printer.