Phaser 7500 leaves black smudges at top of page

[Peter_D]

Thanks for all the help with this - really appreciated!
We are a little charity working in Covid support so thanks!

[GabiE-Xerox]

Yes, you need to replace the affected drum. 

[Peter_D]

Thanks! this is helpful.
When I swap them the problem moves to yellow. 
So one last question - do I need to replace that one or is there something I can do to fix it please?

[GabiE-Xerox]

Hi,

Your problem is from black drum cartridge. Try to swap it with (eg.) yellow drum to see if the issue move to yellow.

Gabi

[Peter_D]

Hi, Any advice would be much appreciated, please.
When printing we get a persistent black smudge.
But it is only on the top edge of the page on the side which is being printed on.
The mark is still there if you print repeated blank pages.
I've cleaned it out and checked the imaging units and toner cartridges for damage.
Any ideas appreciated on how to have a go at fixing this - we are a very very small UK charity and not sure we could afford to call out engineers!