If the image quality is poor even when printing from the machines memory (print properties page) then I am unsure as I would assume that if the image is poor from there then the copies from the machine would have the same problem. There are many things I would check on these machines for cq problems. What have you checked/cleaned/changed so far.
Adjusting codes is usually a last resort for me. The machine changes its voltages to compensate for wear on parts inside the machine.
the image is not poor
the print was not from machine memory but from PC test page, printer properties so this excludes the file format from PC any way I tried PDF,Word,Excel.
it have background black strips on it, it is like the drum cleaning blade dirty, this does not happen in copy
process, in copy process is perfect, I have changed drum unit, developer unit, corona unit, took them from another working copier that prints very good, still the same then I thought maybe it needs AJ code to fix it
and try them to no success.