When you are missing whole lines of text, it may be more than just the print head. But try cleaning the contacts on the print head and the printer with a good, plastic-safe, contact cleaner like Caig Labs DeOxit. Radio Shlock has the Caig Labs contact cleaner pens with the RS label on them.
. Unfortunately, they usually make it impractical to replace the print heads as a whole new printer, with new print head and new carts as well, can often be had for $50. (Canon i455 - amazing at the price!).
. The print head price is $40.08 plus shipping and tax if applicable. But it's not returnable if it doesn't fix the problem... The Canon parts dept is at: 1-732-521-7230 and the hours are 'til 8:00pm eastern.
.bh.