I vote coincedence and the starter is losing the ability to throw the starting pinion far enough to mate with the flywheel...thereby missing and grinding on occasion.

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85 300D 107K present
82 240D 190K present- next-to-slowest car I ever owned
81 240D 1995-2000- slowest car I ever owned
79 350 SE Euro 1996-2001- fastest car I ever owned