One (1) windshield wiper stopped

[bombo]

On my 01 ex sport trac the passenger side wiper stopped working.
The nut at base of wiper dosn't move. The wiper moves by hand with no restriction's.
I'm not sure what I need to check next.

 

[partsman48210]

see if the nut moves while the wipers are on. if so, then it probably stripped the splines on the wiper arm. if not, then remove the cowl and see where it is disconnected