DX4200 Seems to print but nothing on paper

I had a paper jam which cleared eventually having followed the advice here to force a stiff bit of card through. That worked fine but the nozzle check showed blue not printing at all and the rest very blobby, so I cleaned the print heads several times - it used up all the remaining ink. I installed new ink cartridges and tried cleaning again - I have now used up HALF the new ink and I get absolutely nothing on the paper. Where on earth is the ink going?