OK, ran a few electrical tests on the coil & am not convinced it is the culprit.

Primary winding seems OK with continuity between posts & about .15 ohm of resistance. No continuity to ground. Is that too low?

Secondary winding measures about 9k continuity between the output & either Primary post. Again, no continuity to ground.

I am assuming the small diameter Primary post is NEG?

So it seems there are no shorts to ground & it shows continuity where it should, but is the resistance OK or do my readings indicate internal shorts in the coils?

11+ V is present at both primary posts with key on & it drops slightly (about 1V) when cranking.

Removed coil to clean it up & cleaned ground wires connections to mounting bolt. No joy.

Anyone have any thoughts?

__________________
1999 E320 (gave to daughter) 250K
1994 F150 (may be the end of its road) 240K
1989 560 SL (Reassembly after paint job) 160K
1986 560 SL (deceased., gave it's life protecting my wife)
1988 300 TE (departed)
1994 945T (still running strong with an upgraded cam) 349K
1986 242Ti (deceased)
1968 GT500KR (under restoration)