Thanks Chuck.

My hardcover service manual only states:

The blue layer (tungsten oxide) is formed by the arch occurring during the closing stage and the resulting burning of contact material. This arch is above all caused by the discharge of the anti-interference capacitor in the ignition distributor.

A large closing angle (small contact spacing) favors the intensity of the arch and thereby the formation of a layer.

I guess I had better get a CD as I'm finding much of the information in my manual outdated or missing. It was printed in 1994. Oh, BTW what is shielded control line? And, what replaces the female connector in the switchgear? Does it say?

Thanks,
Gympie