Windshield vent-motor runs but vent does not move

[Sobremesa]

Windshield vent motor runs, but does not open. Any suggestion how to service this unit given its location in the crevice of the dash and glass?

[Alumofcu]

If you have a 500, there is an access panel you take off (2 screws).  Gently bang it with a mallet a couple of times.  lube up the shaft that goes up and down.