I would have started with the valve adjust .

You can test the glow plugs from the relay, use the connector unplugged .

? Is there any crud or dark fuel in the clear plastic fuel intake screen next to the injection pump ? .

Let us know how the broken glow plug tip removal goes.....

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better