more likely, cap top need to be replaced, it had happened to me and what I do, is disconnect both lines of ink, going from the cap top to the waste container, close one with a clip and pull the ink from one little how with a syringe some good amount of ink, then close that and do the same with the other one, pull a good amount of ink, connect the hoses back, do a cleaning and you should be ok.
some times, when you are printing and remove the ink cartridge will get dome air.