Black Toner not printing consistently on S4A3 & SRA4 C6501

[G-Graphics]

Hi Everyone,

chasing some help on this issue, machine recently started not printing consistently on one side of the media randomly i have changed black drums and installed 200 PM KIT.
I will attached some images to help as a reference as i am unsure if i am explaining correctly one is a perfectly printed version and a bad version.

Also it doesn't matter what the media stock i am using it happens on everything from 80gsm - 250gsm and even Gloss

Thanks in advance
David

[Synthohol]

stop the image so you can see it on the belt to determine if it happens in development or transfer.
print a solid test pattern at different density look for a pattern.
tape the holes on the DV and swap it for another color, just leave the toner door open so it wont try to add toner.
let us know.