Quick question on heater flaps and how to test.

I want to know if they are functioning properly when closing off the cold air when the heat is on high?
I can hear the servo motors moving but sometimes they appear to hunt a little. I also noticed that the right side vent near the door seems warmer then the centre vents at first when I start the car, but when the car is warm they eventaully all feel equally as warm.

I know the best way is probably to remove the glove box and open up the servos but just wondered if there is a trick to testing them another way?