Same problem with magenta chanel. Printer aquired in january, head fail after aprox 400 sq meters. About one cm of the magenta test print is doubled right in the midle. The print is afected only at high speeds reds. At normal speed is not a problem, at high res is not noticeable (also printing architectural drawings for students or pos posters). I'm still printing with the head, about 650 sq meters now, still doing his job no need to change it althou canon sent me a new one.