Well.. I'm SAD to inform you..your drive has encountered a serious error.
There's a couple of options..none of which you will like.
Drives (SMART) report errors, but sadly don't fix anything. Once a bad-sector has been encountered, its usually an indication of major failure (google/39% of all drives w/bad sectors major failure..etc)
Your options.. Is your data super important--if so, STOP using the drive, send it to a DRC (Data recovery Center), expect to spend $600-1k for the data.
If you've backedup, good news-- drives are cheap.. buy another, plus your drive into tthe 2nd slot, copy off what you can..
the drive itself is having a major failure (meaning it cannot relocate the bad sectors any longer, hence the smart failure)-- meaning-- drives "TRY" to relocate (when they detect failures, they'll move the data else where, mark the bad area, and use a new spot)... Your drive has probably done that.. ALOT. And now... it's gone critical.
BEST solution for you, to save $$ and time.. but a drive ($80-150 bucks)... install your os... put the other drive on the other cable, copy off what you can..and call it a day.
A DRC won't do much more to be honest... if its SUPER critical, contact www.deepspar.com
and see if they will recommend you to a DRC locally to you, or do it them selves...again $$$