Roy are you sure it's a deposit from WD40 and not lacquer of some sort?
If you're working with all metal parts, so solvent won't cause damage, I'd be inclined to start working my way through some of the more agressive ones like acetone (nail varnish remover) and xylene if you can source it. You could also try some of the commercial paint removers and brush cleaners on sale.
Good ventilation and protective gloves etc called for.
Keith