Anyone know how the warming circuit works? As best as I can tell there is a 290 ohm resistor in series with the main element. That will feed a reduced voltage, and thereby reducing the output wattage of the main element for warming indefinitely, with no reference to the coffee temp. I also saw a “rope warming element” for sale for these pots, which has me confused. If anyone has cracked the code, I would love to learn. Thanks.