When the drive detects a bad sector during a write operation it is able to immediately replace it with a spare, effectively "fixing" the problem. But if the error occurs during a read operation the problem is more difficult to solve. As the correct contents of the sector is unknown (and at present unknowable) the sector cannot be immediately replaced. The sector is added to the "Current pending sector count" list. To be replaced one of the following must occur:
1. The sector is later successfully read and it's data obtained.
2. The sector is written to with known data.
The problem is that there is no assurance that either event will ever occur. There really isn't anything you can do about this. Writing to the sector would cause it's replacement but that would result in the loss of it's contents, which may be important.
A small number of "reallocated sector count" or "pending sector count" doesn't necessarily mean the drive is dying but you should continue to monitor the situation. If either strts to rise this could indicate an internal problem and the drivre would need to be replaced.
But above all else be sure you have a backup of all your data. Any drive, new or old, can die at any time, often without warning or apparent cause.
