While I have never come across such an issue, we can discount most of the hardware since it does it on copies as well as prints. (Can't be a defective scanner part)
While it could be something in one of the imaging boards, it could also be a messed up firmware.
I would first reset the thing <All data will be lost> , which is done pretty easily, see here for details.
Failing that, you would need a full on service manual and some real hardware know-how to go deeper.