HVAC air selector stuck on defog (windshield)

[sniperdude]

Hi all,

I have a 1997 Pathfinder with the manual (analog) climate controls. The air vent controller knob is really tight near the rightmost option (windshield defog).

No matter what air option I select on the knob (floor, towards driver, split defog and floor, etc) - the air ALWAYS stays on the defog section near the windshield.

How can I fix this issue? With winter right around the corner, I'd like to figure out what's causing this.