I've had this little printer for about 4 years and haven't used OEM ink in it for several years. I just use it for text printing and it's used OEM ink, carts from Office Max, and most recently OCP ink with no problems. I use the black ink cart only. Recently it started showing horizontal blurring with the Office Max cart, which I refilled with OCP several months ago; it's been working fine up until now. I switched back to an old OEM cart after filling it with OCP and I get the same thing. These little carts have the built-in print head so it looks like the ink must be the problem but if that's the case it sure took a long time to start acting up. Any thoughts?