Prints fine with just 1 sheet of paper in the tray but adding more causes jam in tray 1. It’s been pulled apart and looked at and doesn’t look like anything is wrong or broken
By how many more are we talking about? I've had to deal with a printer in my architecture department, when I was s student, learned quickly that you can't stack too many pages, before the paper would get jammed in the spindle/feed. You might also want to keep an eye on how the paper is tacked since a mild shift in the ream of paper can cause a jam as well.