3 videos. 8 min, 1:45 min and 1:24 min sec to show strange overheating

The gauges run in slo-mo which is why this IVR system works. And the IVR is just a set of points in a small box with a heated wire wrapped around one leg. When the points close, it powers up the heater, which opens the points. As the heater cools, the points close and the cycle endlessly repeats until you turn the key off....... Occasionally, especially with age, the points stick closed longer than they should. At 50% on 50% off the gauges read normally. At 60% on they read high. The IVR is not adjustable. But you can build an electronic one from parts out of a computer, which is what I did in 1999, and my gauges are rock solid/no drifting/no spiking.