The other day I was driving my truck on the freeway and I realized it was in 4 x 4 high. I think when I was cleaning it I hit the switch inside. Now My Truck in stuck in four-wheel-drive. I can switch between high and low but I cannot get it into 2 Wheel Drive. It is a 2007 lariat with 106k. I was thinking of changing the transfer case fluid to start with. Any other suggestions? Thanks