70 Challenger 440: Temp gauge doesn't move. When pulling the wire from the sensor and grounding it the gauge goes to hot as it should. Put a ohm meter on the sensor and resistanse starts to drop as soon as I grab it and raises again when letting go. Tried the same, and got the same result on another old sensor I have. None of them makes the gauge move when mounted and taken for a 10 min. test drive. The ohm meter shows a little different between the when cold - one reads 1.2, the other 0.95. Can they both be bad or am I overlooking something?