are you trying to pull through the waste line?
if so, listen for a hissing noise coming from the capping station when you're doing it.
most likely its a bad seat with the capping station, not making a proper seal when the heads park on it. thus, not refreshing the ink supply.
if this is the case, pull-up gently on the black captop on the capping station. not far enough to remove it, but enough to lift it slightly from its current position. re-parking the head on it should then allow a snug fit and then I'd start with a long nozzle wash followed by a fillupink, observing the waste line to see if the ink is now pulling through the head once again.