Air Mode Knob Broke?

The knob that controls where the air comes out is broke. It is stuck on norm. At first I couldn't turn it to any other setting, but I took the knob off and used a pair of pliars and with much force got it to move. The knob itself is not broken, it's something inside. I can turn it with much force now but the knob goes back to norm. I am going to take it in to get fixed but wanted to know if anyone else has had this problem and was it expensive to fix?