Thanks to those who responded. Meanwhile, with the help of the BBB, I have about got this job whipped. I removes all the stuff on the dash to the right of the steering wheel & then removed the distribution box from below containing the frozen flap, cleaned everything up, lubed some of the housing & flap surfaces that are in contact. It works fine now. The primary problem was that some sorry excuse of a mechanic had simply left out the bolts that mount the flap mechanism to it's housing. During the process I am repairing heater levers which were literally patched with duct tape long enough ago for the adhesive to have disappeared! I found numerous other appalling examples of work in there where the poor PO couldn't see what he was paying for. For those of you who have a Joe Alexander type, thank your lucky stars! The heater lever task is similar to that I did in my 4.5 last year, but I found the 113 levers easier to access & simpler. The job has turned out to be quite an education. Regards -JP-