I have an '05 SLK 350 w/27k miles, delivered in '04. Over the past two years I have encountered randon occurances of the engine not cranking. I have had a new crank sensor and sender installed, a new battery installed and the clutch switch adjusted twice (manual tranny). The car does really well for awhile, then - nothing. I wait, try again and eventually, it starts. I'm never sure if I'm going to be stranded. I even changed keys, didn't matter. This work was all done by the dealer. Any other suggestions are greatfully welcomed. Thanks for reading.