Footnote.com recently replaced the site's search engine. The new version is far more powerful than the old one and is much better at isolating the records you seek, once you get used to syntax. The new search works on both the free and for-pay sections of the site.
Chris Willis, who works on the website at Footnote, has created a tutorial explaining the features of the new search engine. Just look for the link that says "Welcome to Footnote's New Search. See how it works (video)" at the top of any search results page at http://www.footnote.com, or go to http://survey.iarchives.com/fnsurvey/Default.aspx?link=ZCikU8EmS%2friVO7VUyu5oNB9w3%2fEFzEPdZUv848%2b7%2bGnJxxcZM%2b2iBBd4z1rluZy&linkid=246 to view it right now.