Change region code for ink cartridges
I've recently moved from the UK to the US and have successfully changed the region on my Deskjet 6840. Your biggest challenge is going to be navigating through HP's awful customer service (as this is the only way to get it done - don't waste time googling for ways to do it yourself).
After frustrating hours with their on-line tech support, and a useless guy telling me that what I was asking couldn't be done (I should just buy a new printer, apparently!), I turned to phone support.
A very helpful guy on their phone support described to me exactly what was needed. However, he said that it was hardly ever done, many of the tech support people had no experience of it, and that he wasn't allowed to do it himself - I would have to be transferred to "Level 2" tech support. As my printer was out of warranty, this was going to cost me around 40 bucks (I forget the exact amount). Or he said, I could try the online support which, he admitted, was a bit of a lottery.
Given I now understood the "HP terminology" to use, I decided to try online support once more. Probably partly due to the clearer technical description I was able to give, and partly because the person I was connected to wasn't a clueless idiot this time, it was finally resolved pretty smoothly.
Total time taken: 4-5 hours - get comfy, try to not get too frustrated, and don't give up!
HP PSC 1610...
on Feb 02, 2014