C360 black problem

[L0rdC]

Hello, I have a c360 with a problem in printing k, when a print is sent, the black appears completely white or with very little density, however in the color test at 255 it appears as in the attached image, I have tried with new developer unit, drum and transfer belt, contact cleaning and does exactly the same.
any ideas?
52311

[Gaffers01]

is it just the black with the problem?

Upload the prints that show the issue.

Is it just prints or do copies have the issue aswell?