Party Balloons!
 

I had a woodpecker problem at my last house. Nothing seemed to work until I heard about using a shiny helium filled balloon on a string. Something about the movement and sun reflecting on the balloons worked well (2 on a large window). The helium only lasted about a week and needed to do a second time. The woodpecker had found a new place by then. I did have to let my neighbors know I was not throwing a party.

Tape a picture of a shotgun to the window. Or I could loan you a picture of my mother-in-law.

Still think I like the idea of a bb gun or perhaps go back to my roots for a pea shooter

wood pecker
 

Put your clothes on !

Buy inexpensive fake snake or owl and hang/perch above window on gutter.