If the starter does not engage ( engine not turning over ) in park AND in neutral position then it is unlikely to be the NSS switch. It is common for NSS to have pitted contact in Park position but not in Neutral position. It could be the starter. I would try to check whether the starter's small terminal ( solenoid terminal ) gets 12V when you turn the ignition key. Changing the NSS is not difficult but access is tight. I would not go there until you have checked out the starter.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
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1 x 87 300TDT wagon
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