Epson CX11NF laser smearing output with toner (toner recently replaced)

[itm]

I recently replaced the black toner cartridge on my Epson CX11NF multifunction. It's been fine for a few weeks, but is now smearing every printed page with a large streak of black/grey toner (a bit like a skidmark running from the top to the bottom of the page) - see image here:
https://drive.google.com/file/d/1zNMiu0T-OWfDOf2RRzVP2990hAc1LFOi/view?usp=sharing

I guess that this requires something to be cleaned or wiped - would anyone be able to offer any advice?