Hey Jason,
First I would try Moz's SERP analysis tool. Run a report on the page that is ranking, then add the URL of the page that is not ranking, and compare the metrics between the two. Be sure to run a full report.
Oftentimes in these cases, it's not on-page optimization that makes the difference, but backlinks, anchor-text, and site architecture that influence a keyword position in search results.
So things I would look for in comparing these pages:
- What are the backlinks (diversity of sites, types of links, etc)
- Page Authority of each page
- Anchor text of all incoming links to each page
Also, on the other end of the scale you may want to see if any of your pages are actually over-optimized. Too much exact match anchor text? Keyword stuffing?
Regardless, hope this helps! Best of luck with your SEO.