Asked and answered in a previous post, I believe the fix is removing the center panel, doing what's necessary to clean, free up the inner workings.
That looking to be a major adventure, while driving in the rain with the wipers working I thought to turn the dial. It rotates, not great and smooth, but it does rotate.
But when full right, full on, the wipers stopped.
I'm hoping a wizard will tell me that indicates a bad fuze or relay, for an easier fix. I've done a cursory inspection of the fuses, clean and not burned open.