For your situation I would have checked the damper to see if there was ink in the damper and the ink line by the damper. If there wasn't, I would have pinched the red/yellow damper and done a few regular cleanings until the ink came back up the line and into the damper and the print head. By blocking off the other head you save the ink, although it would not be a deal breaker if you did not do that step...
I also would consider pulling with a syringe, but very slowly and with very little pressure to prevent the membrane from being damaged inside the DX4 head.
Someone who is not afraid of cracking the carburetor might remove the damper, syringe the ink into the damper from the manifold opening on the damper. When the damper is full of ink, put it back on the head. For me too risky with cracking the carburetor and dribbling ink on the head board.