Sounds like your printhead is bad. ty running a print test by havind eaither tags or labels in the supply. then clear the machine and press and hod down BOTH arrow buttons at the same tiem and then release. a print test will apear and carefully look for the line that reads BAD DOTS ;
if the value is greater than 000 than the prinithead needs to be replaced

The error # 765 refers to the printhead has less than 4 bad points, press the CLEAR (ESCAPE / CLEAR) and moves the print to avoid the damage. When the printhead has more than 10 points, the error # 768 appear and must be changed.