Removing wiper arm . .
 

I've got a 6volt made in Japan wiper motor on the inside of the cab. The motor shaft goes through a hole in the top of the window frame, as I suspect most do. And then there's the wiper arm. Would like to pull the whole assembly but the arm won't budge. Looking for ideas. I pryed around with an angled pick where the arm attaches to the shaft. Couldn't feel any clasps or tabs. Many thanks in advance.