1) I had no printing both for trichromatic and black cartridge. I noticed that the trichromatic one was almost ended, so I replaced it. The black was about at ⅓ of the full capacity, so I held it.
2) After this operation, I'm facing the new problem that now the printer works well for colour characters, but gives very poor quality for black ones, that is, for instance, the alphabetical characters are represented only in their edges, hence internally they remain white. Please look at the below picture to get an idea. This happens on both Android and Ubuntu platforms.
[3) I had preliminarily done the cleaning of the black cartridge, and alignment of both ones.]
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