First establish which Everdure you have, because the name covers two unrelated product lines with opposite requirements. This page is the legacy Australian kitchen hob. Photograph the burner layout, soak the enamelled parts flat, and lift rather than lever.
One brand name, two completely unrelated appliances, and advice for one that will damage the other. That is the situation with Everdure and it is worth resolving before anything else.
Two Everdures
Everdure by Heston Blumenthal is the current line and it makes barbecues. Its bodies are frequently cast aluminium, and the defining rule there is that caustic cleaner attacks aluminium on contact and etches it permanently.
Legacy Everdure made kitchen appliances in Australia, including this cooktop, and stopped years ago.
The rules do not transfer in either direction. Someone reading barbecue advice and applying it to a kitchen hob will be unnecessarily cautious about products that are fine on enamel. Someone reading kitchen advice and applying it to a Heston barbecue may reach for a degreaser that destroys the body. See how to clean an Everdure BBQ if the outdoor appliance is what you actually have.
This page is the kitchen hob.
What you are working with
An enamelled steel base, cast iron or enamelled steel trivets, and burner caps and crowns sized per burner. Gas throughout, from a period before ceramic and induction became standard in Australian kitchens.
Photograph the layout from directly above before anything comes off. On a hob of this age there is no diagram to consult and no muscle memory to fall back on, and a cap seated on the wrong crown produces a flame that lifts off the ports and will not simmer, which reads as a gas fault rather than a reassembly one.
The method
Lift everything off cold, soak the enamelled parts flat for an hour in hot water with a non-caustic degreaser, work them with a stiff nylon brush rather than wire, and dry cast iron by hand immediately. Our cooktop cleaning guide covers ports, crowns and electrodes.
The base beneath the burners is where the decades have gone, and it wants an oven-cavity approach rather than a wipe: cleaner, a genuine twenty minute dwell, and a second application if the first only lifts the top layer.
Lift, do not lever
Because the line ended years ago, castings are effectively irreplaceable, so a piece that resists should be worked at rather than forced. That is the one place where the age of the appliance changes what you should do rather than merely what you should expect.
What actually goes wrong
Barbecue advice applied here, or kitchen advice applied to a Heston barbecue.
A cracked casting, with nothing to replace it.
A burner that will not simmer, from a cap on the wrong crown.
Rusted cast iron, dried by air.
Should you do it yourself?
Do it yourself, carefully, and give the base the dwell it needs.
Get someone in if the base has decades on it, or alongside the Everdure oven.