Sounds like the motor is messed up its not super hard to change. you could either get a new motor and install it or uninstall the old motor and make sure the gear is in the right direction. I changed the motor in my 92 camaro in about 45 minutes.
You don't say what year you have but it could be the motor. You've probably done this but check the fuse and see if it's blown. A blown fuse is a symptom of a problem, not the problem itself. If it's blown it may mean that the wiper motor is pulling too much current. If that's the case, disconnect the linkage and run the motor. This will tell you if the linkage is binding.
If it's not the fuse, then it is probably the motor. There's a chance it's the wiper switch but that's not very likely.
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