Endeca http service is build on top of the Apache Tomcat, if Tomcat fails to start with whatever reason you should be able to see the corresponding log files under endeca's %ENDECA_ROOT%\workspace\logs folder.
It's possible that the service launcher fails before the tomcat can even start logging anythign, in that case Windows event viewer may have some information.
The JCD in the version 6 is kept only for backward compatibility with v5 installs and shouldn't be used in the brand new v6 and above installations.