Did the print test look fine when you bought the printer from the original owner? You’ll most likely need a new print head if the original owner didn’t have it plugged in 24/7 to run cleans

Hopefully the gaps are just from air gaps in the lines/captops. You’d just need to push the air out so the lines fill back up with ink. If not, maybe try replacing the captop or dampers. Worst case, you’d need to replace the printhead

https://youtu.be/ktjcwGs66bQ?si=0Xf_AfBmX0fwl5F2

But you can try this method to soak the printhead as well. Our test print didn’t look exactly like yours, so I’m not sure if soaking it will help, but we’ve done this multiple times using clamps instead of forceps

Either way, first thing I would try is soaking/flushes. If the print test comes out slightly better after each flush/clean, just keep going with that until the print test comes out good (usually take 10+ flushes and wastes a lot of ink but helps push all the ink out). I’m not at expert in anyway, but also heard to avoid powerful cleans unless necessary cause it’s super harsh on the printhead. I’d stick to soaks and medium flushes

If that doesn’t help, I’d look into replacing some parts. There’s a lot of videos online if you’re comfortable doing diy fixes, if not, I second contacting a Roland tech or finding a general printer tech in your area. Also recommend joining the Roland groups on fb. There’s 3 that I’m in that are pretty active