Aficio cl7300 Black has ghost images

[axyun]

Ghost images on black . Customer had 3 used color drum units. I put them in machine in place of black though I wasn't sure it could be done. Still ghost images on black prints. Any help is appreciated. Frank

[axyun]

It wasn't drum unit as it would be primary suspect. It didn't appear to be transfer belt or fuser as it only did ghosting on the black and not colors.
I now suspect black toner cartridge as I recently had call on Brother MFC9840 with same black ghosting and new drum unit didn't help. Although black toner cartridge was OEM I changed it anyway and that solved problem. This Aficio CL7300 was never co,mpleted as customer did not wish to go farther. Will call customer to advise changing black toner (and make sure OEM). Frank/ActionPhotocopy