Okay, here's the deal.
The early versions that require the upgrade of the resistor, will almost certainly need the upgraded connector. Both are available at the dealer and they will want your VIN to get the right part. Also, from the link posted here a few posts ago, it sounds as if someone found these parts available from a third party source.
If you leave the original connector, it may be burnt, but not easily seen. This is most likely what is giving you the intermittent blower operation.
One poster indicated that there is 12V at the motor all the time. That is the way it's designed. The switch provides different resistance paths on the GROUND side to control motor speed.
As follow up, after upgrading the resistor and connector in my daughters WK back in January, it has run perfectly even during the hellish Texas Summer we're dealing with.
Hope this helps someone,