[Reece]

That is a beautiful chassis, what a job! You might try this on the grille cloth: there is a dry cleaning spray called K2R. I've seen it recently in a large Ace Hardware. It's a dry cleaning fluid in a spray can with something that looks like chalk or talc. I'd try this on a hidden corner first to check compatibility with your cloth. You shake shake shake the can to put the chalk in suspension and spray the cloth. Allow to dry thoroughly, 30 minutes perhaps. The fluid dissolves the dirt and the chalk absorbs the dirty fluid. Then you use a soft brush to remove the chalk. In some cases where the baffle board with cloth attached can be removed from the set you wouldn't have to detach the cloth.