Appreciate the help so far! Now I seem to get:

"Run-time error '5941':
The requested member of the collection does not exist."

Sample text below – the whole purpose is to separate the timecodes into a separate column. (There's actually three spaces between the timecodes and the text in the intended second column, which don't seem to be replicated in quotes text):

15:57:37 When baseball is no longer fun, it's no longer a game. And so, I've played my
15:57:44 last game of ball.
15:57:45
15:57:45 (APPLAUSE)
15:57:45
15:57:47 And so, I've played my last game of ball.
15:57:50
15:57:50 (APPLAUSE)
15:57:50
15:57:50 And so, I've played my last game of ball.
So I'd first find three spaces and replace with a tab. But note that the text still contains some potentially ... limiting ... formatting:

2017-08-25 16_13_54-Macros [Read-Only] - Microsoft Word.jpg

And so, on further inspection, even my initial request wouldn't have helped – merging the cells from each column won't maintain the spacing of the second column if there are blank rows. It turned the above into:

2017-08-25 16_06_36-Document6 - Microsoft Word.png

Anyway, now it seems that it would be sufficient to merely remove the Inside Horizontal Borders, rather than merging the cells within each column, if anybody can help out with that...?