Head works fine. Advice on head replacing: 1. When different kinds of ink being mixed they sometimes produce sludge which kills the printing nozzles. Avoid mixing black and colored ink! Avoid mixing "pigment" and "water solvable" black ink. 1a. Avoid mixing inks in tubes while performing head replacement. Replace inks with special cleaning solution before replacement if not sure (I did). 2. Printers have special "head replacement nozzle purge" operation, consult the "service manual" how to enter the service menu. Using "regular purge" several times in a row is bad for printing head. 3. The photo attached was taken immediately after head replacement (after printer assembly and purge). This printer is 10years old. It prints even better now when all bubbles are gone.
brother mfc6490cw is not incompatible