I see this is your first post. Welcome to the forum.
The search feature here is very good. It should be the first stop when trying to resolve a problem. Having said that, it may be as simple as lubricating the two rods the mechanism rides on. They are right under the large black plastic cover. After releasing the cover, with the wiper stopped in the middle, they are easily oiled(a little ATF works well).
Good luck, Dan