Can anyone suggest what causes these lines across the page?
Is a new toner cartridge likely to fix this?
Edit: Line separation is 62.5mm
Edit 2: Thank you to everyone who replied. I've ordered a new toner cartridge and will update this if that solves the problem ๐ซก
Final update: A new toner cartridge fixed it. It's now printing perfectly! Thank you.
You might be able to see it on the fuser roller but it probably won't be the sort of thing you can wipe off without making it worse.
From the model number shown on your test page (Samsung ML-1660) it looks like a replacement fuser kit is about $30 - $50 dollars depending on the seller. I would encourage you to either replace the fuser or look for a new printer.
According to others it is likely the toner cartridge anyway but where do you find the fuser kits if I decide I need one? I looked on eBay and there are none for sale (in my country anyway).
Swapping the toner cartridge is worth a try. I guess I assumed you had already tried that.
I'm in the US so that is where I looked.
Here's a link to a replacement fuser on AliExpress: https://www.aliexpress.com/item/32961756487.html They might ship to where you are.
I didn't think to look on Ali. You even removed the tracking part from the link too ๐ If it turns out to be that, I'll buy one and replace it. Thank you