I was going to attach a couple of photos but they are too big and I don’t know how to resize them. Anyway, I found a use for old lacquer thinner. Many years ago an old timer, who was younger than I am now, showed me how he used lacquer thinner to clean his spray gun. He would put that thinner in a sealed container and use it the next time that he mixed primer. Lacquer primer didn’t care where the thinner came from. I don’t paint much anymore and never was particularly good at it. But I do have a little used thinner in a container. Getting back to my original post, I decided to use a propane torch to heat up the door panel. I applied heat on the outside while watching the felt liner on the inside. The felt would change to a darker color as it absorbed the melting tar adhesive. I moved the torch in a circular motion so that the metal didn’t turn red. The tar and felt were then scraped off. The next step involved a piece of 30 year old steel wool and the previously mentioned lacquer thinner. The metal cleaned up nice and shiny. The old door panel yielded about 2 square feet of 18ga patch panel that just needs the paint sanded off the outside of the door. Hope that this helps someone who has a similar chore to perform.