2001 Dakota heater blower/resistor problem

I don't know how many people on here still own older Dakotas, but if you do, you're probably well aware of the problem with burned up blower resistors. I've put 3 resistors, 2 pigtails and 2 blower motors in my truck and as of last week, my blower completely stopped working. I read a lot about this, and I've found 3 possible causes: bad ground straps, bad ignition switch, and poor quality replacement blowers. I'm also wondering if a small heater core leak can cause it? My last resistor lasted about 6 months, and I only used it on high for short periods and never used the AC. The consensus is it's caused by high amp draw by the blower. Does anyone have a diagnosis/repair pathway to help me get to the bottom of this problem? It would be great to have a comprehensive answer that covers all 4 possible causes.