I went after everything to get the glow plug lamp to light.
Pulled and tested each glow plug. pulled the GP harness and tested.
Tested relay at each contact. Even tested the bulb.
Followed every procedure I could find in the archive.
Then.... put a grounded alligator clip lead to the ground on the GP dash lamp
and - it lit up. Bent out the connector a little and cleaned out the instrument
cluster hole where it mounts with some 600 grit.
I don't remember seeing this tip in the archive. But not many
people leave there MB out in the back yard for 10 years.
Just sitting causes a lot of oxidation and damage that is hard to describe.
Use it - or lose it.

Used the archive instructions to fix the clock by replacing the two capacitors
as described. It works like new. That is a great piece of info.

Thanks to everyone who helped out.

Good sleuthing and very useful info, has been lots of discussion on bad grounds in recent past. Thanks for posting.

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1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150