I did find two of the elusive clips in Dearborn Michigan so I can get started on the repo of the clips. Since the 72 I have that had the windows has not clips I cannot first hand tell you how they come off. I think West Coast Cougar might have something on their site about them They get $35.00 for the clips when he has them, crazy for such a tiny part.
I will be going to work in the Dayton and Indy. region in a couple weeks and will work with a shop there to get something going on the clips.
I believe that if you pop the door panel loose you have to go behind the panel and release the clips to get the bezel off before you can remove the panel all the way. I am going to do both the drivers bezel clips and the single control clips they are the same for 70 - 72 on Mustang, Cougar, T-Bird and some big Fords.
I will post on the Forum when I have them for sale and they for sure won't be $35.00 each.
I would suggest you take the window guides out clean all the old grease off and use the Lucas Oil Products, Inc. RED "N" TACKY #2 grease to lube the tracks and rollers. You should also pull the regulators and clean the teeth and pull the gears out of the PW and clean and replace grease. The front window gears are everywhere on eBay and not difficult to find. The rear motors, "Pancake" motors are hens teeth. The West Coast Cougar site has a video on how to take them apart and clean and lube. The will do repairs and rebuilds also. They are usually worse than the fronts as far as dried up grease and rust. You will probably need to blast them and get the case re plated if you have a supplier. If not just paint them. You will be shocked how fast they go up and down after cleaning and new lube and quite no shaking. No real special tools needed just time a patience.
David