Can I repair/reuse a dying hard drive?

Yes, you can, indeed, repair it. However, it's sort of pointless. The end result would lead to you buying a second drive, swapping the platters (to clear up the platter damage and bad sectors), possibly flashing or replacing the interface board to reset the SMART data....literally, building a new drive in the hull of the old one. Which requires the parts from another drive...rendering your whole repair pointless.

Unless there's something you're just desperate to keep, 2TB WD Greens tend to go on sale on Amazon often, and are pretty inexpensive now in general (under $70). I'd Data Recover what you can if there's anything left, get a Torx screwdriver, pull it apart, and begin your project of a mirror made out of dead HDD platters.

HDD platters are the core of the device and are where the data lives. Often, bad sectors means that the thin metal that is lain over the glass platter is becoming pitted or not able to be magnetized anymore. Older model platters are no more durable, even though they are usually solid metal. Some really old ones even have precious metal cores. In all cases, when the sector can't be magnetized, it becomes useless to the drive. There's no real coming back from that.

Short answer: No.

A failing hard-drive shouldn't be used anymore. You can perform a low-level format ("it requires that each sector should be overwritten with zeroes") but it will only mark bad sectors to not be used, (2). It is only a short term fix as it will most likely have more bad sectors as time goes on.

Even if there was a fix / some sort of repairing it, it would be only temporary and a dying drive (especially an old and heavily used drive) is dying.