I purchased an used Hp Designjet 8000s a couple of months ago. It was very well maintained. At the very beginning I did not have any problem but for the last 3-4 weeks I've been having problems with the black printhead. Evry single morning it is clogged and I have to do a lot of printhead cleaning to be able to make it work again. I am not using OEM HP inks so I guess that there could be the problem...but at the very beginning I used the same inks and didn't have the problem. Any thoughts?