I have a 99 RS about a week ago I was changing the air direction on the dash when it got really tight. I was changing from defrost to the floor vent. When it got tight I started to turn the knob back to the defrost setting and all of a suddon there was a thud and then there was nothing I can move the knob freely but the air positions do not change. Has anyone encountered this? If not has anyone taken apart the dash and could help me with it? Thanks