I wonder if the cps being faulty caused some issue with the rotor. Maybe intermittent reading or signaling caused arching? Not sure.

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1990 190E 3.0L

Doubt it. All the crank sensors and all the other ignition stuff I've replaced since 1988 on those cars, it's never come up. Yours would not have been the first after all these years. Now, I've not done hundred like Iluvmils or somebody like him but it's likely you had 2 problems the whole time. If there is a connection, I would love to see it.