Canon Pixma TS8250 banding issue

[Frank fingers]

I have a Canon Pixma TS8250, about a year old. It has started to print thin blue horizontal lines across all pictures. All the inks are showing as full. I have cleaned it using the maintenance function twice and done a deep clean, but still no good. When I have printed a nozzle check pattern, the yellow band is coming out grey, though after one of the cleans, it it was yellow with a thick grey band through the middle. Doea this mean the head is dirty and needs a manual clean? I've attached two images - one of the banding, and one of the nozzle check pattern wiht grey through the yellow. Thanks for nay help on offer