I used to stop them at idle with my hand, gloves on. showing how a clutch should operate, but one of my techs whack his finger hard showing how I did it to another tech on a car with a bad clutch.

You could tell the clutch was fully engaged (full size truck) as it was pulling in some serious air.

I'm just a little more careful as to what I say to others now.

Allen Here's a novel idea, let's not throw a bunch of parts at the car hoping it will fix the problem and instead spend a little time diagnosing it first. Life was a little easier when I was just a wrench.