Hi nerdwarrior, You should change this Terminal Block. Here is a picture I made from the terminal block to see the connector lip in half way closed position.   The material in here is Tin plated Copper. Maybe we can see this lip if you turn the screw clockwise to lift the lip. Did the wires for the heat bed show any sign of overheated, burnt black etc.? If you touch (trying to heat) the PT100 resistor with your finger, there should not be any big jump in the reading - maybe 1 ohm "mo