Found my dads original 1971 duster!
Thanks. Ya, mine have a different tab than that. You push it out with a flat screwdriver. I push it while prying and it literallg doesn’t budge. I’ll try to take a decent pictureAre you releasing them? They have a lock that has to be released before they come off. Can't find a picture right now, sorry.
Worst case, I would pull the arm off the motor so you can at least rotate the wipers. You will have to do it by feel as it is up under the dash, but just takes a 3/8 or 7/16 socket. Center of the dash, way up at the top.
Looks like this:
