While starting my 911 SC last week, the starter suddenly stopped cranking. It has always started well and now will only push start. There is an audible click from under the engine when I turn the ignition to start posistion. How should I begin diagnosing the problem to eliminate the easy inexpensive fixes (fuses, fusible links, starter relay, etc) before going to starter replacement. The car has less than 10,000 miles on a rebuilt custom engine.