Air Flow Selector "stuck"

[roccgirl]

I have a '08 4-door Barcelona Red Yaris S. This morning I had to run the defrost. Went to town for lunch and when I tried to switch to vents, I felt a bit of resistance. I turned selector knob back toward defrost to loosen (this happens all the time), and when I tried to go back to vents there is now ZERO tension and the air is stuck coming out of the floor and defrost.

Question is: How much of a PIA is this going to be to fix? I am not afraid ot tear into a car to fix something :) All help is appreciated. Problem isn't too annoying today, since weather is nice, but may drive me nuts in a few days when it gets warmer again.