The bad plugs had that screw; see pic here.
So if they made ones with a screw which were OK, that just means the trouble was due to the resistor. That’s fairly obvious really; the screw system should be fine. And they admitted it was the resistor…
Lots of things used to be good and then became crap.
The last set of Tempest URHM38S plugs are behaving now (values in k ohms)
Got a new set of values. Unfortunately I did not mark the plugs, but at least I have where they came from: T=top B=bottom cyls
