When I bought mine from an old hippie in north Washington state it stunk like bigfoot’s rear until I pulled out the seats and all the carpet too. It makes a big difference replacing the jute under the carpet. Found three old dried up joints and a handful of beer bottle caps trapped in the back...
I had the same problem with mine. The felt or jute was seriously stinking up the car.
The felt is held down by a tar material. I ripped out all the felt I could then used a wire brush in a circular motion. You can use a torch or a heat gun to heat the tar up a bit and burn the "hairs" left...