Photograph the layout, lift the trivets, caps and crowns, and soak the enamelled parts flat in a non-caustic degreaser for an hour. Identify the hob by its model number rather than its badge, because Ariston parts cross-reference under Hotpoint and Indesit.
Ariston hobs in Australian kitchens are predominantly Italian gas: enamelled steel or cast iron trivets over enamelled burner bases, sold through apartments and mid-market kitchens over the last two decades.
Identify by model, not by badge
Ariston has been sold here under several names, including Hotpoint-Ariston, and shares components with Indesit across the Whirlpool group. A burner cap or a trivet that appears unavailable under one name is frequently listed under another.
The model plate is usually on the underside of the hob, which means looking up from inside the cabinet below rather than at the appliance itself. Photograph it while you are down there. On a fifteen year old hob it is the difference between finding a part in ten minutes and concluding it does not exist.
The caps and crowns are sized per burner
Ariston hobs typically carry three or four burner sizes. Caps and crowns are matched to each, and a large cap seated on a medium crown sits proud so the flame lifts off the ports and the burner will not hold a simmer.
That fault reads as a gas supply problem and is a reassembly problem. It is the most common complaint after any multi-size gas hob is cleaned, and it is entirely prevented by photographing the hob from directly above before anything comes off.
The base underneath is the real deposit
With the burners lifted, what remains is the enamelled base of the hob, and on an older Ariston that is where the years have gone. Every boil-over has run down there and been baked by the burner above it.
Treat it like an oven cavity rather than a benchtop: a non-caustic cleaner, a genuine twenty minute dwell, and work rather than a wipe. Keep liquid off the ignition electrodes beside each burner, or they click without lighting until they dry out.
Our cooktop cleaning guide covers the general method, including what a glass Ariston needs if yours is ceramic rather than gas.
Dry the cast iron by hand
Exposed iron rusts within hours in a Sydney summer. Dry every trivet and cap completely by hand rather than leaving them to air, and deal with the first orange patch promptly, because a piece that has been left wet once tends to keep rusting at the same spot.
See how to clean an Ariston oven below, which is usually the same age and in the same condition.
Pan supports that have warped
On the older Ariston hobs the trivets are enamelled steel wire rather than heavy cast iron, and steel wire behaves differently over a long life.
Cast iron either survives or cracks. Steel wire slowly deforms, particularly under a heavy pan on a burner that runs hot, and a warped support does not announce itself. What happens instead is that pans start sitting fractionally off level, which produces uneven cooking in a frying pan and a wobble that gets blamed on the benchtop or on the pan.
Check by putting a straight edge across each support on a flat surface once the trivets are out for a soak. It takes a moment while they are off anyway, and a warped one is inexpensive to replace once you know the model number.
What actually goes wrong
A parts search under the wrong badge.
A burner that will not simmer, from a cap on the wrong crown.
Rusted trivets, dried by air.
Ports enlarged with a metal pin, which changes the gas-to-air mix permanently.
Should you do it yourself?
Do it yourself, lifting the burners every month or two before the base sets hard.
Get someone in if the hob base has years of build-up, or if a burner has become unreliable and you would rather not diagnose it.