Aha, so with these hints, I figured it out.
It takes a spark plug socket, and in the loosening direction,it locks and removes the spark plug.
Then in the tightening direction that blade notch engages a spring ball and clicks at a preset torque.
From the feel of it, that spring is worn out and clicks too easily.
Maybe why there aren’t many around anymore?
Curious, does anyone use a torque wrench on spark plugs?
I never have. Just going by the pressure needed to compress the
Washer on a new plug. Not very much in pounds!
Thank you all for looking at this🤓