It wasn't raining, but I had to use the water pump/wiper this am. Sounded like they were going across a rocky road; it was like the wiper blade was skipping across the windshield. . The wiper blades are a year or so old, still soft to the touch, and the pivoting parts on the arm move ok.

Any thoughts here ?

Wiper blades are consumable and should be replaced yearly for best results.

With that said, try a little talc to help them slide.

I just got new blades and a day later I was in a thunderstorm. Heavy rain was fine on either speed. But a light mist had the slow speed skipping a bit. So I just used the higher speed wiper setting. Not much difference in the two speeds but the faster setting had no skipping. Also, hard surface protectant applied on the windscreen makes all but the heaviest rainfall wick off the windshield without the need for wipers. But given how much I see Porsches advertised as "never driven in rain", I guess this is a rather useless thread for most people here.

If it rained in Phoenix I might drive in it.

OK; I applied moisturizing cream to the wiper blade and smoothed out the wipers.

A bit off topic but I've ruined new Bosch blades by using RainX
The rubber turned to a black smeer on the glass.