Mercedes Benz repair: 1983 240D Turn key nothing happens, mercedes benz 240d, neutral safety switch

Question
I just got this 1983 240d, I used it the first day to go to work. It seem to start fine till I stopped at the store on the way home. I tried turning the key and nothing happend. After trying to turn it over numerous times with nothing happening I finally called AAA
and had it towed home. Where do I go from here?
Help!!!

Answer
Clean battery terminals.
Inspect ground strap, from engine to body, clean or replace.
Test battery.
NOTE:
You must have at least a fifty AMP charger, and it will take hours to charge a low DIESEL battery.

If problem remains, test the Neutral Safety Switch, read all these threads.

http://www.mercedesshop.com/shopforum/showthread.php3?p=564003#post564003

http://www.mercedesshop.com/shopforum/showthread.php3?p=424700#post424700

http://www.mercedesshop.com/shopforum/showthread.php3?p=419422#post419422

PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1983 Mercedes Benz 240D
Part: Neutral Safety Switch
 Note:  Aluminum case
J4050-66317 Neutral Safety Switch IN STOCK $59.78  
  
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=merc...