Hi. Great to find others having the same struggle as me. I am currently overhauling a Panoram 4-D. It was in really rough shape when I got it, but the price was right and I've always wanted a Panoram. I spent weeks of my spare time trying do my homework and prevent harming the camera in my efforts to revive it. There just doesn't seem to be any info out there on repairing these. Finally, I couldn't wait any longer and I just jumped in with both feet.
I am not sure if the mechanism that swings the lens on your camera is the same as the one on mine. This 4-D has all of the important parts (springs, swingarms, etc.) above the lens, with only the rod that the lens pivots on extending down to the bottom. Seems like I've seen some photos of a Panoram with gears on the bottom - mine has none. If this is the case with yours then this might not work for you.
To remove the central rod that the lens pivots on- loosen the screw at its base from under the camera. This screw is small and the access hole is too, so it might be hidden by gunk that has built up in it. This hole is directly under where the bottom of the rod meets the camera body.
Also there is a small square nut located on this screw on the interior. This is held secure by a small nail that is easily pulled with needle nose pliers. You may need to also loosen this nut before turning the screw, but I am not completely sure of this yet.
After this screw is loosened, the rod should slip out. You will have to remove the knurled ring on the lens that secures the bellows if you want to remove it completely.
Hope this gets you moving forward. I've been playing with the spring drive and have some thoughts on it too. As for the leather- I have been searching for a source and have found the Levant Grain from www.ganebrothers.com to be the closest so far. But I'm still looking. I like the chamois idea - my bellows has BIG holes in it.
I'll post some photos as soon as I can - preparing for possible hurricane and school has me wrapped up at the moment.