Windows – Chkdsk consistently failing due to no free space but it has 90% free space

I have a drive that I suspect is a bit borked but none of the sensors or alerts have gone off on it. Regardless I decided to move important files out of it before replacing it.

But any move operations take for ever (sometimes it transfer at full speeds but then it ocassionally drops to few Kb/s) and ocassionally fail to IO error.

So I decided to run a chkdsk on it. But then I get this failure:

Insufficient disk space to fix volume bitmap. CHKDSK aborted.

That really shouldn't be the case. I had basically deleted as much as possible from the disk and it's current usage is:

fsutil volume diskfree k:
Total # of free bytes        : 923025682432
Total # of bytes             : 1000202039296
Total # of avail free bytes  : 923025682432

In other words I have 923GB free in a 1TB disk. There's no reason for chkdsk to fail. Is there something I can do to get chkdsk to finish running, so that I retrieve a couple of files?

Here's the full output from chkdsk:

C:\>chkdsk /X K:
The type of the file system is NTFS.
Volume label is Secondary.

Stage 1: Examining basic file system structure ...
  354560 file records processed.
File verification completed.
  8 large file records processed.
  0 bad file records processed.

Stage 2: Examining file name linkage ...
  370206 index entries processed.
Index verification completed.
  0 unindexed files scanned.
  0 unindexed files recovered.

Stage 3: Examining security descriptors ...
Security descriptor verification completed.
  7823 data files processed.
CHKDSK discovered free space marked as allocated in the volume bitmap.
Insufficient disk space to fix volume bitmap.  CHKDSK aborted.