This requires a cleaning of the print heads. You can find this cleaning program under the catagory “inkt” with the term “cleaning” (this term may vary by printer) on your Brother printer. This proces can be repeated a couple of times.
By clicking on the link, Guide for Brother printers, you are redirected to the site with Brother printers. Here you can select your printer from the list and then download the manual. The manual describes how to clean the printheads, how to align the printheads and how you can check the ink levels.
