wrote:

.... good info snipped...

We've recently had trouble with AC plugs; the internal resistor
seems to be failing. Champs have had that problem for years.

Dan,
I recently used my Fluke 77 DMM to check eight Champion REM40E
spark plugs, which have a built in radio suppression resistor. I
measured Ohms between center electrodes and threads (all Open). I then
measured the resistance through the center electrode from the wire end
to the electrode end, and noticed that two of eight plugs were "Open"
(10MegOhm), while the other six ranged from 1.4K to about 7K.

I expected all of these to be the same resistance, but was surprised at
the variablity plug to plug. I am puzzled at the two that read open.
They were not misfiring before removal. What's going on?

btw- I also measured 12 brand-new RHM40Es; 4 of 12 were open end to
end???