Well. Here's the latest. I removed the vent and I found the problem. The wheel on the side that adjusts the output air flow up and down also connects to a flap on the inside that blocks the air from getting to the vent. The wheel is connected to a lever which is connected to a cam that the vent flap connects to.
So the connection between the wheel and the flap came apart. There's a nub that rides in a grove and it came out. When it is out you can turn the wheel, but the vent won't open, only close.
After putting the nub back into the grove and reinstalling the vent everything works fine.
