Upper fuser roller HL-L8260CDW replacement

My printer prints a small mark several times on each page. I inspected the drum unit and found there is a scratch on the fuser roller for the black toner. It is quite severe and I want to replace it. So far, I have not found a video or manual on how to replace that part of the fuser unit. I can buy a replacement fuser unit, but it costs half the price of the printer. And because the printer has not yet been used that much, I don’t want to replace it completely.
If anyone can tell/show me how to replace that specific part in the unit, I would be much obliged. I think I may have found the replacement part on AliExpress for a reasonable price, so that would repair the printer.