Hello Tom,
This is more than likely a mechanical fault, although I'd advise to remove ink cartridge/s and put them back in again in case the problem lies within the alignment of the catridge/s.
If it's in its first year, Canon deal with the repair of their printers. Their number should be 08705 143 723 - charged at a national rate so no absurd call costs or anything like that. Even if it's not a mechanical fault, they'll know exactly what you need to do to fix it.
Hope this helps,
Mike