[wwest]

I would suggest that the blower motor is connected backward resulting a low airflow, but at the same time with it turning backwards less "work" is being done resulting in a lower current flow for the motor, less heating of the resistors.

The alternate explanation. Carpet, etc, is so seriously blocking passenger inlet side flow that most of the system air flow is via the driver's side.

Then again... With that one contact gap being so narrow it may be being closed partially from the heat radiating from the opposite resistor. It then closes resulting in more heating of the opposite resistor thereby keeping it closed indefinitely.

So adjusting the gap may well have resolved the issue.