Thanks! Worked like a dream (after downloading again from icomoon without embedding the fonts).
In summary for others, here is the whole process:
1. Visit the icomoon site, and select the symbols you would like to include in your font (as shown in the tutorial video for preference and circumference)
2. When downloading the updated font information, use the default download preferences (without embedding the font)
3. Copy the new icomoon font files (.eot, svg, ttf and woff) from the newly downloaded fonts folder to a fonts directory in your child theme
4. Open the newly downloaded styles.css file,copy its content then go to WP and edit your child theme’s css.
5. As mentioned above, paste the modifications into your child theme’s css above your custom modifications.
Note: I deleted most of the new CSS since it duplicates the Circumference theme’s style sheet and just left the modified path information and specific references to the new symbols (example below) in the child theme css file.