2000 saltwater II starter problem

[Boater#1]

I have a 2000 150 saltwaterII motor 9 times out of 10 the starter works but sometimes it just does not engage just makes a noise.Is the starter going bad? Also sometimes when I turn the motor off it does not kill it right away maybe 4-5 sec's later bad switch? Thanks for your help!

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sounds like u got corrosion building up somewhere