When looking at a problem posted at the WCF forums (http://forums.microsoft.com/MSDN/ShowForum.aspx?ForumID=118&SiteID=1), I usually try to set up a local reproduction of the issue to understand what is going on. One thing that helps me the most is to have a few templates that I can use to get a head start in the investigation. This very small piece of code can come quite handy for most of the issues I've seen so far:
Hope this helps.