Quote

You need to read the instructions, it's very well explained there. Not only that, but you are missing some more information.
Check the OP again, and the next few posts after that one.

OK, did more reading, although I don't have a complete grasp of this. I ran
C:\btcrecover-master\extract-scripts>extract-bitcoincore-mkey.py c:\btcrecover-m
aster\wallet.dat
Partial Bitcoin Core encrypted master key, salt, iter_count, and crc in base64:
YmxxxxxxqaVIxxxxxxxx6PjjUxxxxxxh/Jaxxxxxx8x/GCitxxxxxxxxDxxxxxxx21

and got above long string
then ran:
C:\btcrecover-master>btcrecover.py --data-extract --passwordlist
Starting btcrecover 0.17.9 on Python 2.7.13 32-bit, 16-bit unicodes, 32-bit ints

Please enter the data from the extract script
> YmxxxxxxqaVIxxxxxxxx6PjjUxxxxxxh/Jaxxxxxx8x/GCitxxxxxxxxDxxxxxxx21
Please enter your password guesses, one per line (with no extra spaces)
Use exit() or Ctrl-Z plus Return to exit
password1
password2
password3

exit
Wallet difficulty: 61,696 SHA-512 iterations
Using 1 worker thread
5 of 7 [#################################--------------] 0:00:09, ETA: 0:00:03
Password found: 'xxxxxxxxxxxxxxxxxxxxxx'

How do I get the private key out of the script? More reading ?

Thanks for all your help.
Tried pywallet --dumpwallet on it again but was no help.
I think I have the answer bitcoin-tool ... but having trouble compiling it.