I should have mentioned earlier, this baby's history isn't THAT suspect.
The PO's receipts (from 1998-2003) show that 30k ago (in '98), she had a FULL VALVE JOB, including:
REBUILDING THE HEAD ($740) and cleaning, reinstalling, new head gasket, adjusting valves, etc, to the total tune of $2000.

That's a GREAT step-by-step from 300SDog, really appreciated. But man, I'll tell you, it's the kind of job I'd sure like to SEE done (or have a veteran looking over my shoulder) before I attempt it personally/alone.

If I'm going to start by the easiest route:

-Can I get that spring + keeper off and inspect that valve without removing the camshaft housing?

-Do need to buy/build a spring compressor to get that one off, or can I work it with some other handy household tool?

-Once I get the springs and stuff off, how is an idiot like me going to diagnose a dislodged valve retainer bit, bent valve stem, or seized/slipped guide (with nothing to compare it to)? Will it be obvious?

-Is there ANY chance that all this could just be caused by a "collapsed" valve adjuster screw / threaded bushing?

__________________
-lee
'83 300CDT (286k)

former proud owner of:
'85 mercedes euro 300TD
'80 mercedes 300TD
'77 mercedes 280e
'80 mercedes euro 250
'82 mercedes euro 250