Thanks Lori,
It happened that right before or after I posted this question that there were posts about waterproofing on the forum in other places. They mentioned the spray silicone waterproofing product "Waterguard", I have a can of it and will test it on my old no longer waterproof jacket. The product claims to let the fabric breath. We'll see. My jacket was a Colombia, but it's been washed so many times it's not even water resistant now.
I will have to look up "pit zips".
ATB

edit- got it! vents in the armpit area which zip open to vent or breath.