Rather than continue asking about this question as part of this thread, I am starting a new one.
I have replaced the circuit breaker and the whistle controller diode and resistor on my KW. The whistle diode works, but if I short the A and U terminals with a jumper and slowly turn up the speed control it does not trip the breaker and the light does not come on. It looks like this:
I tried resoldering the lamp resistor wire. Using a VOM, it seems to have some resistance (although I don't know what the specific resistance is supposed to be. The lamp does not appear to be burned out (there is continuity across it). I changed the automotive circuit breaker to see if it was defective. (Littlefuse 10A) I used pigtails with spade terminals to make changing it easy.
I have the service manual for it which includes pictorials, but I have been a little reluctant to completely disassemble it. There was a smoking problem when I was messing with the whistle diode / sound activation button described in the other thread.
The transformer works on both sides. The whistle controller works as well and the smoking has stopped.
What would be the "most likely" reason for the circuit breaker not tripping?
I have attached the complete service manual for those who may want it and don't have one.