|"can I assume new files will be okay?"|
It depends, but I suggest that you save everything that you can right away and replace the drive.
It sounds like one of the platters was damaged. If some of the platter surface was scraped off and is floating around in the drive, that can be very bad. It is likely to get caught in between another head and another place on one of the platters. This can cause more damage and pretty soon you have a massive failure.