I've had this exact same issue with my 164-S, that I purchased new, since it was a few years old. I have shimmed up my hood the same way that you did. I doubt that there is a problem with shimming down the wiper spindle as long there is no interference with moving parts and you have full engagement of all threads on the spindle nut (Loctite blue may help too).
I believe that the real issue is that the wiper arm, between the spindle mount and the flex joint bends (just what you've photographed above). I've seen threads on how it can be bent back but perhaps a new arm is a better, albeit still temporary, solution.
Last edited by IRONBLOCK; 06-06-2017 at 10:42 AM.