Repairing Sagging Headliner (ceiling) (roof) on a VS Commodore

First of all, I had no idea what I was doing when I started this project.

Vacuum Cleaner
Phillips screwdriver
Small flat head screwdriver
750 ml Shelly's wood glue (or similar product)
Hard bristled brush

I removed all the roof fittings (all held with philips screws). The clips covering the screws for the passenger hand grips are easily moved with a small flat head screwdriver.

I removed the cloth from the cardboard backing. On reflection, maybe this could have waited until I had removed the cardboard backing from the car..

I cleaned the deteriorated foam/glue from the back of the cloth with a hard bristle brush while my helper held the cloth against a wall. It can be done on the floor but eventually some the the deteriorated foam/glue gets on the good side of the cloth, making a new mess to be cleaned up.

I pulled down the seal at the top of the doors. They come down easily with fingers.

I removed or partially removed all associated molding by carefully pulling on both sides of the molding at each clip until the clip released. I laid both the front seats back flat and then maneuvered the cardboard backing out the front passenger door.

I used a vacuum cleaner to remove most of the deteriorated foam/glue from the cardboard backing and to clean up the deteriorated foam/glue from my work area floor.

I then used a paint brush to apply Shellys wood glue to the cardboard backing, being careful not to get too much glue on the hundreds of holes in the cardboard. It is easy to miss the indentations, so be sure to get glue into all of them. I then aligned the cloth with the cardboard and with a helper slowly lowering the cloth onto the cardboard while I used a small dry paint roller to smooth the cloth. Stretch the cloth a little temporarily towards the front to be sure there is enough cloth to go into the indentations. I wasn't careful around the edges, thinking that those will be covered by molding. However, the front edge is not covered by molding so be sure to spend some time making that edge look good.

I let the glue dry overnight and put it back in the car through the front passenger door. Then with a tiny amount of liquid nails I reattached the three "pads" to the top of the cardboard liner.

I then held the liner to the roof and reattached all the fittings and carefully pressed the moldings back in place. Job done.

Finally, I couldn't find a temperature rating for the glue I used, and because the car roof gets so hot, another product might be more suitable.