Replacing the headliner is a delicate and painstaking job, but the results are well worth it! It is so nice not to have it flopping on your head when you are in the car! And of course, the new one is clean, without the decades of dust, grime, stink, and cigarette smoke accumulation. It is not difficult nor complicated, but there is a constant risk of cracking or breaking the old wooden frame inside that stretches the headliner tight. You will need to be very careful handling this. An extra set of hands will be necessary for some things.
The basics of how this assembly works: the vinyl headliner is stretched over a thin wooden frame and stapled to the back side. There are three metal slats or ribs running side to side that hold the center of the headliner up to the roof. The frame uses the same kind of clips as the door cards or interior upholstery cards to snap into holes in the edges of the roof shell. There are no fasteners visible once installed.
It was hard to figure out how this all goes together until I started disassembling it. When I took it down, I discovered that the loops on the back of the headliner had failed, like thomcarp197 describes above. The springy metal slats slide through these sleeves and hold the headliner tight up against the roof. Except the sleeves are vinyl “welded” or melted to the main piece on the back side, and when these welds fail, the headliner hangs down. Here are a few pictures of my replacement, hopefully they will help you see what is going on.
To take the headliner down, you will have to remove the mirror, mirror mounting plate, sun visor clips and sun visors. Feel around on the edges and locate the clips. Use one of those plastic upholstery tools shaped like a crow-bar to slide between the headliner frame and the car shell and carefully pry them out.
Here you can see two of the three sleeves just completely separated and the third starting to fail on the edges. Check out all that filthy gunk!
Here is the exposed wooden frame with all the old clips and staples removed.
I found that setting the new work on the roof of the car was the perfect shape to support everything correctly. There is quite a bit of stapling and trimming required with the new headliner.
New headliner fit to the frame. Next replace all the clips into the oval holes in the wooden frame (new ones are available). Slide the slats through the sleeves and try to keep them in the same order that they came from. Getting the assembly back inside the car is a little tricky and you could use some help. It does fit through a door opening. Once you have the slat ends back in place on one side you can spring the other sides in, and this will lightly hold the headliner assembly up. Then begin aligning and popping all the clips back into their holes in the roof shell.
In the end the old wooden frame held up fine despite all the pulling, stapling, twisting and handling.
The finished installation is so gratifying! Good luck!