How Do I Keep Open the Exhaust Damper

So, I've always know there is that exhaust damper in the right exhaust pipe that opens and closes as it likes. I never had a problem with it causing a bit less sound, making it look a bit asymmetrical in the winter with the exhaust fume, or the fact that you can see right into it from behind on a sunny day. However, today I noticed my exhaust looked like this after my first snowy drive...











Because its not letting as much exhaust fume out when it closes and reopens it was really getting noticeably dirty and caked on with crap. Does anyone know how to open it and keep it open??