How should I proceed with this damaged and repaired Hard Drive - Win 10

Background:   Dell 17 Inch Model P26e
Computer was running very slowly, and would just hang during Explorer operations.

I managed to get it to boot to Safe Mode, and copied the User folder to an external USB drive using program called "Beyond Compare" which I trusted more than a plain windows copy.

I then booted from a Win 10 DVD, navigated to Command Prompt, and ran  chkdsk /f/r

The first few times it ran chkdsk crashed with an unknown error during "looking for bad clusters in user file data"   It did find and mark some bad clusters.  The file names looked to be various App data files.
Since I didn't get any errors when copying to USB drive, can I assume that the damage wasn't in the User folder?

I'm now at 4th pass.

This most recent run of chkdsk:
Stage 1: 4 bad file records processed
State 2:  0 unindexed files canned
Stage 3: Usn Journal Verification completed
Stage 4: File data verification completed

Stage 5: Bad, free clusters
It took a while to get past the 0% (maybe an hour)   It's now at Stage: 8%   Total 17%  and progressing steadily.  (ETA is 12:00:17)

I now need to figure out how to proceed should chkdsk finish.
Should I assume that the hard drive is failing, and purchase a new internal SATA?

I have a Orico brand Dual Bay USB 3.0   2.5 and 3.5 SATA Hard Drive Dock, which has firmware to duplicate drives.
I figured that I should see how well the computer runs now, do SFC / scannow,

How can I clean out all the caches and temporary files?
I don't want to copy over damaged files and settings (if any)

How should I proceed?


Thanks