I have tryed to clear, what colour is clogged with one drop of spring water on each inside ink "hole" as You told to do with alcohol.
Position BK, Black, takes the drop in immediately and after some drops I can see water on tissue at output. Yellow ,Y, is also good as well as PGBK.
Magenta and Cyan took spring water very litle in the colour channel. But it took somewhat so that there were coloured water on the paper tissue.
At last no more coloured water.
Then I tested it wice versa; spring water on output. Water drops dropped down out from YL and BK and PGBK from inner ink "holes".
There was water drop keeping inner hole - not dropping out, although continuing put water on outer "holes".
TEST AFTER CLEANING AND AIR CLEANING
There is still the same error U052 on the printers screen.
Does the printer give error U052 if there is still blockage?
Should the memory of the printer to be resetted, and how to do it?
What You recomment next?