First a small correction, the tractor is a 2002 TC40D.
To determine the wattage I have a device called Kill A Watt EZ I purchased on Amazon. You can plug in a device, let it run for a number of hours, enter in your electricity cost per kilowatt, and it will display how much electricity the device used and how much it costs to run that device per hour, per day and per year. The meter indicated that the block heater consumed 8.7KW over a 21 hour period or about 414 watts per hour. I spot checked just now and it indicated 420 watts and 3.4 amps. When I plug in the block heater I can faintly hear it sizzle and this is normal from previous years. I measured the resistance at the three pins of the heater. They are not labeled. The resistance between the outer pins is 34 ohms. The resistance between the outer pins and the center pin or the block is infinity or open.
The glow plug circuit is working normal, the battery is new and indicated just over 12 volts (Red Optima with 800 CCA) The engine is not turning over quickly, that is the problem. It has been so cold, sub zero, that the engine will need to be heated in order for the engine to turn over quickly enough to start. In the past that only required the block heater to be plugged in for a few hours.
Just now I touched the heater itself and it felt warm but not hot after being connected for 10 minutes. I have never touched it before so an not sure if this is normal.