best tool to check external hdd for errors

[thedeadghost]

Hi !
I have a external hdd seagate expansion backup plus 1 tb. Recently i noticed some of the snaps have developed a green layer on them. I have moved remaining on another pc some i cannot copy due to error. is it signs of bad sectors ? Can i fix it ?
Thanks !

 

[nRiTeCh]

Yes, bad sectors probably. Inspect your drive in seagate tools and hd tune and hd sentinel and post the results!
How old is the drive btw.