You really should use distilled water. Yes you could try hot or warm water. Soak the print head bottom in a tray, with just a little water to cover bottom. Acetone, nail polish remover, etc, on a cotton swab might work.
Put it back in, continue running head cleans and see what happens.
Try printing a large yellow square. Keep cleaning, do head cleaning and head alignment and eventually it may clear up. Check the head status under Ink info>printheads> from the main panel.
If it doesn't work - you may have to spring for a new print head. That may be your best bet, because you will loose ink doing continual head cleanings. Print heads are innexpensive, relatively speaking.
Be sure to remove the print head using the front panel selection under INKS, and follow directions after installing, which just means close carriage cover and latch, close printer cover and let the printer go through its routine, testing, calibrating and aligning, etc. - takes about 18 minutes, and prints out a sheet. Do a color calibration and see if yellow has come back.
Try printing, just keep going - eventually it may come back.
