Have you checked the lines from the captop to the pump are completely free and all the connections? and also that the pump is working properly? If the pump doesn't clear the captop properly then ink can sit in it and soak back up into the head. Normally a bad head plate will give you really badly deflecting nozzles, and apart from the colour mixing yours seem ok
You can check the pump by putting cleaning fluid into all the captops, then turning the pump by hand and see if all the fluid is sucked out of the captops equally