Check out the link, about 3/4 of the way down there is a post that describes what and where to clean.
83 300D Turbo
You might try tightening the starter and cleaning the described connections. Apparently the diesels are touchy about corrosion, probably due to their load at startup.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.