wind pushes windshield wipers up at highway speeds

['68 383 Charger]

While driving my '68 charger with 2-speed wipers 60 MPH or faster, my wipers will move up the window in their normal arc, has anyone had this happen? is it the motor going bad, or something in the linkage. When I stop, I push the wipers back down where they should be very easily, making me think my motor is going bad. thoughts and or ideas?

 

[oldbee]

More inclined to go with worn linkage, could also be the knurling wearing out on wiper arms/or the end they mount to.