I often wonder how many times chuckG will start this thread

Your wiper transmission has probably failed, it has a feature that extends and retracts the blade as to wipe the top left corner.
It's a $1400 part
It's a fairly common problem and many have found it to be a gear that breaks inside the tranmission. A few have had a new gear made and put it in with success. I've tried but couldn't get the transmission apart, i drive with it broken now. No big deal.