[Arran]

I think that the toners used were light walnut over the bulk of the cabinet, except the grille, and medium to dark walnut (not extra dark) on the shoulder sections at the top, and at the base. In answer to your question about the grill bars, those appear to be solid walnut so I would put them back to the way it left the factory, with no toner. If it was cheap wood like poplar I would say to go for it but this is one of those rare occasions in which it is real.
Regards
Arran