Yes, I could see the photos now. Does the metal bracket slides over the knob? I can't see it in the photo, I would consider some J-b weld. It dries hard as metal and I have used it in some interesting places and it sure is strong. Does the metal bracket swivel on the other piece, can you see if it was originally tack welded and that broke. If the fabric could be removed a weld would be best. Closer up photos would help. Also have you spoke to an auto upholsterer. They may offer some advice. They surely have encountered this before.
