Sometimes when you refill a HP or Lexmark cartridge you get the dreaded message "Cartridge Not Recognized". What does this mean? It recognized the cartridge before I refilled it!

HP and Lexmark have the print heads right on the cartridge and if you'll
notice there is some circuitry on the side which also has electrical contacts that connect the print head to the printer. There are many contact points that must be made between the cartridge and the printer. If the connection isn't perfect you will get the error message.

There are a couple of things you can do to rectify this. First try snapping
the cartridge in and out a few times. If that doesn't work remove the
cartridge and clean off the foil contacts with a Q-Tip dampened with alcohol.

Be careful not to wipe the nozzles, where the ink comes out, or you
might contaminate the ink inside the cartridge.

Before you put the cartridge back in use another Q-Tip dampened with
alcohol and clean off the contacts inside your printer where the cartridge
connects.

Some printers will be difficult and keep giving you the error message, or
will report wrong ink levels in the ink monitor. In this case turn the printer
off and unplug it from the wall. Wait about 20 - 30 minutes and try it again.

Also try rotating between 3 different cartridges when refilling. Some
printers remember the last two or three cartridges and can give you
problems if you keep installing the same refilled cartridge.

If you have an HP and the printer prints but the ink levels are not right you
probably need to do the "Tape Trick" Follow the links below for the type
of cartridge you are refilling for the correct procedure.

HP cartridges #'s 15, 45, 78
http://www.repeatotype.com/instructions/HPReset.pdf

HP cartridges #'s 56, 27
http://www.repeatotype.com/instructions/HP56Reset.pdf

HP cartridges #'s 57, 28
http://www.repeatotype.com/instructions/HP57Reset.pdf