Paper feeder is creating lines on original. How to clean or fix.

Check how much waste ink is in the service station on that printer, if you can do this. Open the ink replacement area on the printer and use a high-power flashlight to make sure you can see. If you see a good amount of ink there (or it's full), it's coming from there. HP's WIC pads on the "compact" series (like HP 60 series models) which use tri-color carts with integrated heads that are puny and last 2-3 years before it becomes a chronic issue. If I ever need to get them for some very rare reason, I consider them disposable after 1 year of use with how much ink they dump there and how fast it fills. To make it worse, HP LETS YOU RUN THE PRINTER UNTIL IT LEAKS INK (even right after).

The pad can be cleaned (but it's messy, wear gloves and work on a cleanable surface) but if it’s at that point you either have a ton of pages, other wear issues, or high pages (10k is high on these... yep). Most of them are towards the end of their life. TBF, I chuck them when I get stuck with them in a hardware deal at the nearest site a few miles away; I don't have a use for them 9/10 times, or it's got this exact problem!

If you don’t see any significant ink buildup, the problem is likely coming from the rollers from a heavy print that didn't dry quickly enough (or just dirty ink from the service station seal). Clean both of these parts with a slightly wet paper towel for completeness just to make sure you got the problem fixed.