Win 11 wi-fi, no errors, print head removed and cleaned, replaced cartridges, etc etc and as I said my printout looks exactly like API posted above. Wavy lines through the middle of the black grid. The workaround suggested by someone is to print your documents in, in my case Dark Lime...evidently that eliminates the printer using the large black cartridge (labeled PGBK) and solves the problem. I did not clean the timing tape.
