Current_Pending_Sector and Offline_Uncorrectable

Can someone explain whether or not these increasing actually means your drive needs to be replaced? I see such varied responses when googling. My drive has a raw value of 10 for Current_Pending_Sector and 1 for Offline_Uncorrectable. My GSmartControl is yelling at me constantly, but it's just those same values. Do I actually need to replace the drive? It *is* almost eight years old, so I plan to anyway, but I just want to understand and make sure I don't replace things unnecessarily.