The transfer roller is responsible for transferring the toner particles from the drum to the paper. If the transfer roller is damaged or worn, it may not transfer the toner properly, resulting in poor quality printing with missing print or unreadable pages. Exchanging the transfer roller is a common solution to fix this issue, as it is a relatively simple and straightforward process. The technician will need to remove the old transfer roller, install a new one, and run a few test prints to make sure it is working properly.