I was refilling the black toner and filled it to 95% but after a day I realized that I should not, so I poured toner back into the bottle (emptied cartridge) and filled it to 50% again. No printing was done in between.
Pages printed since then look very good, thick text. However some pages have some smudge at the top. Some pages have it, some not. After printing 60 pages, I see it more often on those at the end. Pages printed first are okay.
What can be causing it? And how to get rid of this?
