Note that there was an announcement (Jan. 9, 2014) by Ford that 2010-2013 Edge and MKX vehicles built at the Oakville Assembly Plant from May 3, 2010 through March 28, 2013 are having the brake booster warranty extended to ten years or 150,000 miles.
If you are having a problem with the brake booster you should be able to get it fixed for free. I was just looking at ordering parts and attempting it myself - so glad I found this.
Its in a letter with subject "Customer Satisfaction Program 13N02"
The letter is posted in the thread at http://www.fordedgeforum.com/topic/13888-13n02-extended-warranty-coverage-on-brake-booster/