Thanks for answering. I live in the US and I need one as fast as possible. All of a sudden my prints are way off color and a print test keeps showing trouble with the magenta having lines. I refill with Precision inks. I have done numerous cleanings. It won't let me do a print head alignment and gives error 255 I think. From everything i've been reading the magenta is a common problem with this printer and I just assumed it is a bad print head. I use the printer daily for black printing and now have a large project coming up where I need color. I would consider a new photo printer if I can refill and really don't need another large format.
It could be the cartridge. In fact, it's likely. Just replace it with a new one. It's a lot cheaper and more available than a head, and the worst that can happen is that you have another known, good cartridge. Then read this thread: http://www.printerknowledge.com/threads/flushing-why.9217/ .
If the lines are real systematic and regular, that would indicate an electronic or head problem. If the problem is a little streakiness or feathering out at the end of each stroke, it could be either head or cartridge, but more likely a cartridge thing, I think.
Have you tried Canon, USA parts department? They have the cheapest print heads in the USA, and they should be available for 5 years (or so)...
Genuine Canon replacement service parts, including inkjet printer print heads are available to purchase by calling the Canon Parts Order Desk at (866) 481-2569.