if none of the mentioned procedures works,,,then better do one thing,,
you cab swap the print head with the nearest one & give a FILLUP,,,a cleaning too..
then go for a tst draw,,,if the problem changes the position thn its better to change that particular print head,, bcoz i belive it hav physical damage with the nozzles which is very dificult to see with ur bare eyes,,,,all the very best,,thnx