I did as you suggested and can now access the Index. On opening this, the first thing I did was to compare the number of entries in it (41,748) with the number shown in the file info' (41,904). I cannot explain this difference of 156.
Starting at the top, I then went down the Index to see if anything stood out as being out of order. I came across a couple of blanks which I marked and un-successfully tried to delete. I then came across a person named "Blake" whose name appeared in the middle of a group of people named "Black". I was unable to either open this record or mark and delete it. I then thought I might be able to get rid of it if it had some connection with others and that I could delete a group that included it. I couldn't find any connection with others, so am stuck with it.
Could you please let me know if and how you were able to delete similar types of un-wanted people from your file.
Rather than writing to you direct, I thought it might help others with similar problems if we continued this exchange through the forum.