I have a Canon MP610 printer which smears a vicious (!) streak of black ink on the reverse of all my prints, gradually reducing in severity with subsequent prints but always visible.
I have tried all the cleaning routines available in the Canon Printer Utility, cleaned all accessible parts in and around the printer "carriage" and have replaced both black cartridges, all to no avail.
While it doesn't mar or obscure the actual printed side of the page (much), it looks ugly and it's clearly wasting ink. I am about to submit an online support request to the Canon Australian website but I'm not particularly confident in an early response. Does anyone have any ideas what, apart from buying another printer, I can try next?
iMac 21.5 in, late 2009, 3.06 GHz, Core 2 Duo, 8GB, Lion 10.7.2