@savageray ,renalesraymond, Read through the links below, 1st link is the procedure to change SOV . 2nd and 3rd link is good info. Good luck.
I hope this helped you out, if so let me know by pressing the helpful button.
http://www.dieselgiant.com/repairyourshutoffvalve.htm
https://www.youtube.com/watch?v=ohDmGj8WU4w
https://community.cartalk.com/t/1984-mercedes-300d-turbodiesel-wont-stop/38832/3