Wiper problems

Hi,

maybe a common problem:
When i turn my wiper switch i can clearly hear the motor working. It increases speed on the second position too but the wiper arms wont move even a bit.
I can move them by hand easily without any resistance doesnt matter if the wiper motor runs or not.
Is there a gearbox that tends to brake on these motors?
If yes is it fixable?

Thank you guys.
Author: sebastian