I have been doing recovery on hard drives for a long time and know when it's time to send it off. This is also why I am trying to get everything setup with other drives first, so I don't put additional strain on the potentially bad drive.
I learned a personal lesson a number of years ago. I wanted to copy a bunch of vacation pics from my laptop to one of my Linux servers for a backup, but I accidentally moved them and one day, the server crashed. The platters were actually scratched from the heads. Total loss.
The pros have a lot of tricks before they go to the clean room. One is to switch circuit boards from a good identical drive
Dave