Lift the trivets, caps and crowns after photographing the layout, and soak the enamelled parts flat in a non-caustic degreaser for an hour. On a hob this age the enamelled base underneath will need a genuine dwell rather than a wipe.
Baumatic hobs came into Australian apartments as part of matched developer packages, and the range leans gas with enamelled trivets.
The base underneath is the real job
On a hob that has been in an apartment for fifteen years and has never had its burners lifted, the surface you can see is not the problem. The enamelled base beneath the trivets is.
Every boil-over across that time has run down there and been baked by the burner above it. Because it is entirely hidden in normal use, it carries the longest continuous history of anything on the appliance, and it is frequently the reason a hob smells when the burners are lit despite looking acceptable from above.
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. Expect a second application on a hob that has never been opened.
The general method for lifting burners, clearing ports and looking after the electrodes is on our cooktop cleaning guide.
Photograph before you lift
Caps and crowns are sized per burner, and on a hob nobody has ever taken apart there is no muscle memory to fall back on. A large cap seated on a medium crown gives a flame that lifts off the ports and will not simmer, which reads as a gas fault and is a reassembly fault.
The package around it
The hob sits between a Baumatic oven and a Baumatic rangehood of identical age, and the hood is the reason the hob keeps getting greasy.
Drying, and why it matters more in an apartment
Cast iron and enamelled steel trivets rust quickly in Sydney if they are left damp, and an apartment kitchen makes that worse rather than better.
These kitchens are frequently interior rooms with limited ventilation and a rangehood that has not extracted properly in years, so ambient humidity after cooking stays higher for longer than it would in a house with a window over the sink. Trivets left to air dry on a draining board in that environment stay wet for a surprisingly long time.
Dry every piece by hand, completely, straight after rinsing. If a trivet has already developed an orange patch, deal with it promptly, because a piece that has been left wet once tends to keep rusting at the same spot rather than stabilising.
What actually goes wrong
A hob base with fifteen years on it, because the burners have never come off.
A burner that will not simmer, from a cap on the wrong crown.
Rusted trivets, dried by air rather than by hand.
Should you do it yourself?
Do it yourself, lifting the burners for the first time and then every month or two after.
Get someone in if the base has set hard, or for the matched package in one visit.