OK, lets break this down.
I'm going to assume a white void on A4 size copies.
1. Does it happen from the ADF as well as flat off the platen (glass)?
2. Does it happen along the direction of paper travel if on the adf or against it?
3. On the glass is it following the line the light travels or up and down?
4. Does it also happen on prints or internal pages (configuration sheet)?
wc5755 text or image quality problem original A4 size paper center or front side white line. how to slove