Thanks Ducks,

That got me further, but not all the way.

With this search string (.*?)(\#)(\d+)\s(.*?)_ (a blank space at the end)
Test text of: Woodworker's Journal #142 Jul-Aug 2000 results in 1422000
The addition of \s has removed the text "Jul-Aug " from the result, but not the following number. Without the trailing space that text string is not removed.

Edit:
But adding \d+ after the trailing space resulted in just the volume number. Someone needs to explain why \s(.*?) \d+ would capture Jul-Aug 2000 and (.*?) would not