I'm just in the process of recovering my seat and plan on reusing the fiber layer that was on the bottom cushion, but not the cotton batting. I got the seat covers and installation kit from Jim Carter and they provided burlap (1st layer) felt (2nd layer) and cotton batting (3rd and 4th layers), along with the covers. The original cotton was gone where the driver sits and pretty funky elsewhere (signs of mold, etc.) The cotton layer came off the fiber layer, which is in pretty good shape, in some areas but not in others, so used a wire brush to get the remnants off. Kind of like shearing sheep.
I think the fiber layer will work better than felt, but like Jon said, the cotton is going away.
