Yeah, I would say that you need to get more than 60. It depends on the HDD's characteristics, of course.
You need to test the drive with any of the tools in the link I've provided. The test results should provide a S.M.A.R.T. report which will show the overall health status of the drive. In case there is something wrong with the drive(like bad sectors), you need to back up the data.
Another thing you can do is to defragment the HDD.
D_Know_WD