The Stovebolt Site Forums The Shop Area Interiors 1938 Vacuum Windshield Wiper Motor

Mike - I would use a narrow-long jawed pair of vise grip pliers (like pictured below) that would probably fit the exposed shaft. I would try a thin piece of older leather or rubber strip wrapped tightly around the shaft and lock on the the vise grip pliers over what ever you wrap it with to hold the shaft while you try and turn that center end nut. Be sure to soak that nut down with some penetrating fluid before trying to loosen it up. I think this would hold the shaft and not mar it significantly while trying to take it apart.

On an after thought, did you look around the sides of that cup held on the shaft. Be sure their isn't a hole in the side that might lead to a set screw that might secure that end piece to the shaft.