Brother TN227C High-Yield Toner Cartridge Cyan TN227C - Best Buy
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Amazon.com: 1-Pack (Black) Compatible High Yield TN223 (TN-223BK) Laser Printer Toner Cartridge Used for Brother MFC-L3750CDW MFC-L3770CDW Printer (with Chip) : Office Products
Brother MFC-3770CDW never seen this before, appears to be software related? This is the test print function, have changed black toner with OEM : r/printers