Hi, they can be very stubborn if they’ve never been off. I usually just lift the arm off the screen and give it a damn good wiggle in all directions (holding the arm not the wiper). They usually work free eventually. Giving it another dose of wd40 all around where it “slides” onto the spindle...
Was hoping to put this old girl back on the road but it’s not gonna happen now so may break if anyone needs anything. Got a few decent extras like pillar speakers and pop out opening rear windows etc. Drop me a message and we’ll go from there, thanks