This may or may not work, but try this.  Remove the cyan cartridge and give it the stander roll & shake, making sure this is done carefully.  Don't want to get any toner on your clothes.  If you're brave, you may even want to open the toner cartridge and make sure there's no obstructions to the opening.  (I take no responsiblity for anything that might happen while doing this!)  There is also, what I think is a "head cleaner".  If you open the top cover, on the right side there's a lever you can pull out about an inch.  This opens a small door on the right side of the printer housing.  Inside is a small handle that you can pull out and push back in.  On the end of this "stick" is what looks like a small cleaning pad.  Give that a brush a couple times and see if that clears things up.  (This option is a lot easier.)