cooker hob

Soak overnight in detergent, scrub with bicarbonate of soda - then put through the dishwasher?

I have a Neff gas hob, and the care instructions say that the cast iron? stands are not dishwasher proof. But others may be OK.

Put on newpaper, preferably outside, and spray with oven cleaner. Leave for a while, then handling with rubber gloves, rinse. Might depend on type of stands though. some are cast iron, others some other kind of metal.