Printing Errors or Lights & Stuck Print Jobs

My laserjet printer has started ghosting faint images of the sections of the black ink image, ~6.3cm down the page from the properly printed original part, and producing some vertical lines. [edit to add] The ghosting isn't all the way across the width, just on a few stripes down the page of which there are several, which are all black but faint enough further down that you can see the ghosting. The rest of the page is fine.

I looked into it already and realise it could be fuser or another of the rollers,  but its hard to get in and measure the diameter of the rollers to be sure which one. That gap indicates a 2cm diameter one (6.3/pi). Its strange that I haven't seen it happen for any other colours though, which makes me wonder if its related to the cartridge; which is a newer one (but I don't remember it starting to happen straight after I replaced it, can't swear on that). Can anyone confirm what cause is most likely with those symptoms, which rollers are that diameter / is it more than one thing? Thinking it might be harder to get it seen by someone for a while longer (in lockdown still in the UK). I've seen the ghosting on card and paper (and I set the print settings to tell it the weight, and buy stuff suitable for laser printers not the inkjet plasticised stuff).