Very helpful post. Give it your thumb action!

Ted, the Mitchell drawing makes it appear the red wire from the switch to the motor is continuous, but as you discovered it is not -- interrupted where the resistor's blue wire attaches. That's where your interruption occurred, so any test to prove the motor is getting power has to be made at the last uninterrupted motor wiring, which really does include the ground. There's no shortcut that does not result in an assumption based on likelihood.

In our email yesterday, I sent you this photo, which illustrates the connection you found to have failed -- in the aftermarket version of the resistor-switch harness. If the blue wire would fail, the blower would still work on max speed, but if the red wire fails (as yours did) you get nothing.



Here's one that better illustrates the topic of the thread.



--
Art Benstein near Baltimore

You have to stay in shape. My grandmother started walking five miles a day when she was 60. She's 97 today and we have no idea where she is.