|Yes, it's always best quote your operating system in the first post if it is different to the spec. I know little about Mac's but this still sounds more like an issue with the printer itself.|
I don't know that particular printer either, so other than taking the head out and putting it back in again there's not much more I can suggest. You could carefully clean the contacts, otherwise If it still plays up it must either be a faulty print head (unlikely as it's new) or the printer itself has failed.
Keep watching in case anyone else has a bright idea.
Always pop back and let us know the outcome - thanks