heater controls

[old tiff]

no air coming out of 2 vents in middle of dash. took them out and the spring loaded flap beind does not open. I have a 1985 with the rotary controls just above the vents. looks like i will have to take the whole panel off?
the are 2 wing nuts inside when the vents are removed. what else needs to come off to reconect the switch to the flap??
may as well do it while its raining.