Thanks for your input.

The first EZL failed with a new Beru coil.

The second with an older genuine MB on I had in stock.

The third failed with another, different, new Beru coil.

This afternoon I installed a new, genuine MB coil.

I cleaned and copper greased all the connections and checked earth/ground resistances - all close to 0.2 ohms as measured from the battery negative. This is a great improvement on initial measurements after the third failure.

Next week, the local garage will install a "new", remanufactured Bosch (genuine?) starter motor and alternator. He will be instructed to check, clean and reinstall all cables, including the engine earth strap.

Beyond that, I'm lost!!!!

Yes, it's an expensive business. The car is operational now with my new 1200€ EZL. I've ordered another used EZL for 220€ and I shall use that one until confidence returns. The new one will be with me at all times, together with the tools to replace.

And I may get yet another used one for safety.

This may make me sound very rich - not true. I spent some cash getting my old 300CE-24 restored as my "last car" - I'm 68. So, I cannot go back; I MUST resolve this.

Life's fun isn't it?

Ray