Tedious work inside the driver door removing stock sound deadening. I'm no expert on such things, but the research I've done seems to indicate that a constraining layer damper makes the interior quieter by preventing (or minimizing) vibration, and it does this being elastic, and being bonded to the panel. This tired old stuff is more brittle than elastic, and is somewhat adhered, but also pulling up in many places, so it probably isn't doing much to quiet anything down any more.
I tried a freeze spray, but it didn't do much other than the lube part of it softened the adhesive slightly at the very edges. The parts that weren't adhered pulled off in gratifying big chunks, but the rest came off slowly with lots of scraping with a very thin flexible putty knife in little tiny chunks. After an hour or maybe a bit more, the end is in sight, and my arms are getting sore!
At this point I switched to a single-edge razor blade and WD-40. The brown bits are adhesive that is stuck to the door skin after breaking/scraping the rubber/tar/paper (or whatever it is) off.
After a wash and solvent wipe down it will be ready for new (and much more effective) sound deadening. 😅 I think I've got room in here for a new constrained layer damper right on the inside of the outer door skin, then a waterproof melamine/foam sound-absorbing sheet on top of that, plus a fibrous sound-absorbing and decoupling layer between the inner door skin and the door card.
