[EricS]

I'm a little late to this party, but had good success cleaning original grille cloth with an old toothbrush and my air compressor. There wasn't much actual soil on it, but it was heavily caked with dust and drips of one sort or another.

After a few minutes, it looked pretty nice. Careful with the air pressure thought, don't get too close to the fabric until you know how sturdy the fabric is.