YSK Your laser printer may be forcing you to buy unnecessary and expensive toner by displaying low toner messages before it is empty and refusing to print. You can save hundreds (thousands?)
Brother - MFC Series - TonerWorld
Brother Printer Not Recognizing New Toner Cartridge - Fixed
How to reset Drum /Toner Brother MFC-9970 printer /how to enter Hidden reset menu - YouTube
How to reset Drum /Toner Brother MFC-9970 printer /how to enter Hidden reset menu - YouTube