Heater resistor?

No draw with the fan switch turned off, and yes I’m testing with the key in the run position.
The ground sounds like a possible culprit; how does the blower motor and resistor ground? Is there an easy way to put a jump lead to ground and see if that solves the issue, and if so where should I connect the ground lead to the resistor
Resistor does not ground. It is in series with the motor hot lead. The motor (as I recall) should have a brown lead with an eyelet that wanders around somewhere in there. Look around up by the antenna, under the pass side cowl vent can, etc.