I know this is an old thread, but thought if I added some info it may help someone.
When I purchased our Disco, the liner was sagging real bad so I pulled it out and gave it the "once over". I removed the felt and foam backing as best that I could, then bought a 4 litre container of Turps and soaked the liner while scrubbing to get the glue off, then let dry for a couple of days. After I was happy all the turps had evaporated I used fence stain (had it in the garage) and painted it all over the liner, turned out brilliant. The stain soaked in real well, I was using black stain but it came out a nice darkish grey, I think it looks mint :cool:
I will never have a sagging liner again and the part itself looks like it was made that way. If anyone wants a pic, I will post one up.
I hope this might help someone who does not want to spend $$$$$ on getting the liner re-done.

