Okay so I'm having some starter issues. When i turn the key its as if the starter isn't catching or grabbing whatever gear it needs to grab to start cranking the engine. It takes 3 to 4 tries to get it to "grab" whatever it does to get the engine to crank. What is it's problem?

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1973 280 - Sold
1980 300SD - Sold
1982 240D - Stolen
1988 300E - Sold
1989 260E - Sold
1989 560SEL
1994 E420 - Sold
1997 E420
2005 CL500