I engaged 4x4 on the way to work since it was icy but as I pulled in and tried to disengage while rolling but it was stuck. Waited until I parked and tried again but would only let me go to 4L. Now it won't let me go back to 4H and definitely not back to 2. Any ideas? It's got about 700 miles. Maybe it's just stiff but didn't want to force it.