The switch is bad or dirty. Probably the latter. Take it apart snd spray it with brake kleen or electrical cleaner. They're both the same ingredients. If that doesn't work, the switch is bad all together. The grinding noise could be something in the track. Make sure there isn't change Binding it up.

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Only diesels in this driveway.
2005 E320 CDI 243k Black/Black
2008 Chevy 3500HD Duramax 340k
2004 Chevy 2500HD Duramax 220k