Here's a quick follow-up.
This morning, going to work, it was snowing......

So I spayed the wiper posts with WD-40, in fact I drowned them in the stuff...

Turned the wipers on, they blocked half way.

I helped them a bit, and after a couple back and forth, bingo, they worked by themselves.

So I spayed again just to make sure, they even picked up speed a bit which I find encouraging, and off I went.

They worked fine all the way.

So I guess it was a bit of jamming temporarily solved with a bit of lube.

Will disassemble, clean and lube and hope this will cure the problem.

Thanks again to Emily's dad for the tip !!! Rep points to you !!!