Color print cartridges contain three or more colors. Usually the primary colors from which all colors can be made. The levels of each color will drop at a different rate depending on how much each color is used. For instance if you are printing pictures or web pages that contain a lot of yellow such as this page you'll be lowering the yellow level faster than say red. Since there's very little red on this page at all you'll barely use it when making a hard copy of it. The fact that you are only getting pink could very well mean that you are out of or running low on the other colors. Some printers come with a utility that monitors each color separately so you can go out and get a new cartridge when you can see you are about to run out. If your printer doesn't have such a utility then it's a safe bet to either replace or refill your existing cartridge.
It could also be the case that the jets on the cartridge have become clogged which can be remedied by simply blotting it on a damp sponge and allowing it time to dry before using it.
If cleaning the cartridge and or replacing it/ refilling it doesn't solve the problem then you most likely have some sort of physical damage to the printer such as a damaged ribbon; though I wouldn't worry about this until you've tried everything else first.
I have some crappy lexmark z series printer and recently its started printing in nothing but pink. I assume this because of the cartridge. My question is, if i just refill it will it be fine or is this the sign of a broken cartridge?
-CE

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