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Based on what you've said about the black dots and assuming they're always in the same place, it is more than likely the black drum that has a fault, but it could also be the fuser unit and/or rollers.
Try a test print to see if the other colours come out ok (or alternatively print in the other colours one at a time to see if you get the same issue). If you get the same issue, it would be worth trying to wipe down the rollers first with a lightly dampened lint-free cloth. If that doesn't work then it's likely the drum or fuser and unfortunately, it's a process of elimination. Replace the drum first and if you have no joy, try a new fuser.