It would still likely be sharper than the defective Pigment Black. The problem is that Photo Paper mode uses more ink than what plain paper can accept, but changing the text color from black to a dark gray before printing should resolve that. When the proper amount of ink is used, the difference...
Try wiping the clear tape with fine lines that runs behind the carriage. If that doesn't work, then tape over the gold terminals of the print head and carefully rinse out the large pigment black channel. Does the quality improve when the text is printed in gray color and photo paper mode (which...