I would clone them and then run data recovery software against the clones. Do this via SATA, not USB.
These are the tools the pros use:
https://www.hddoracle.com/viewtopic.php?f=36&t=3208
If your drives start to stumble, then clone them with HDDSuperClone or OpenSuperCLone (both open source):
https://www.reddit.com/r/datarecoverysoftware/wiki/hddsuperclone_guide/
BTW, the free version of DMDE is limited to 4000 files of any size from any one folder per click. The standard version (unlimited) costs US$20.
You could try running CHKDSK in read-only mode (not repair mode). If it runs, it should tell you which metafiles are damaged. Running CHKDSK in repair mode is dangerous when your drive has serious problems. That's because Microsoft cares more about the integrity of the file system and will often sacrifice your files to this end.