I searched for weeks for a simple fix to my sagging headliner woes. But eventually I had to give up on looking for advice and bite the bullet. Here is what I did:
I carefully pulled the headline loose on the driver side where it clips in the door frame. Next I reached in and removed the first three bows, the headliner had roted out from under the bows so there was no hope of repair. I reattached the headliner over the drivers door and got things back the way they where before starting the job. Finlay I reinserted the headliner bows on top of the old headliner, just poke each bow through the headliner.
Overall it does not look that bad, if you were not looking for it you would not notice the metal bows, and I still have my headliner. Considering how long I suffered with a headliner hitting my in the face, and that this fix took 5 minutes, I can say it was something I should have tried years ago.
In looking at it more, either the last owner had reused old headliners during their restoration attempts, or more likely, they had put some sort of chemical on the bows, like a glue compound, that could not stand up to the heat of the metal roof and broke down the vinyl.
Just thought I could contribute my fix, David Tucker