I understand the principle of a heat sink. That's exactly why I would expect to see discoloration at the base of the screw as the heat originates and radiates through the screw -- before the heat sink effect occurs. If the heat originated at the base, and there is minimal heat sink effect happening there, wouldn't the discoloration be there also?

So, Mr. Richard Roshak...
It's up to you now. You must go to the job, disconnect the power by yanking the meter, and remove the set screw in question. At that point, you must carefully photograph it and look for any signs of poor contact or anything else that looks odd. After that, you must carefully retorque the screw to the mfr's stated requirements (with new anti-ox goo), restore the meter to it's rightful position, and sneak back out of there.

Then let us all know what you found. Got it?

We're all counting on you.*


* Just kidding.