Clean it gently and deliberately, because parts are the constraint rather than the method. Kleenmaid's 2009 administration left many of these appliances orphaned, so a glass panel or a door seal you break may simply not be replaceable.
Kleenmaid went into administration in 2009 and later relaunched under different ownership, and the ovens installed before that point are still in a great many Sydney kitchens.
Parts scarcity is the real constraint
On most appliances the question when cleaning is what you might damage. On a Kleenmaid of that era the question is what you might damage that cannot be replaced.
A door glass panel, an inner door trim, a specific shelf runner or a model-specific seal may simply not exist in the supply chain any more. That does not make the oven fragile, but it does change the calculation. A risk worth taking on a five year old mass-market oven, such as levering a stubborn trim or dismantling a door to reach between the panes, is not worth taking here.
The practical rule is to clean thoroughly and dismantle conservatively. If a fixing resists, stop rather than persist.
Many are Italian-made under contract
A useful thing about the older Kleenmaid range is that a good deal of it was manufactured in Italy under contract rather than built in-house. Cavities, fixings and some components cross-reference to European models of the same era, which occasionally turns an unobtainable part into an obtainable one under another name.
It is worth photographing the rating plate and searching by dimensions rather than by brand when you need something.
The cavity itself
Almost all are plain vitreous enamel with no self-clean, so the method is the standard one: soak the racks separately, apply a non-caustic cleaner with a genuine thirty minute dwell, work it firmly, and repeat rather than escalate. Our oven cleaning guide covers it in full.
Almost every Kleenmaid we open is fifteen years old or more, so expect carbon rather than grease and expect two or three applications.
When to stop cleaning and start deciding
There is a point on an orphaned appliance where the honest advice stops being about cleaning.
A Kleenmaid that is structurally sound, seals properly and holds temperature is worth maintaining indefinitely, and these were well built. But if the door seal has perished and cannot be sourced, or the cavity enamel has chipped through to steel and rusted across a wide area, no clean addresses it and no part fixes it.
That is worth establishing before spending an afternoon or paying for a service, rather than after. The seal test takes ten seconds: close the door on a sheet of paper and pull, and if it slides out freely the seal has stopped compressing.
What actually goes wrong
A broken part that cannot be replaced, which turns a cleaning job into an appliance decision.
One application and a conclusion, on carbon that needed three.
A perished seal that may or may not be sourceable, and is worth checking before it fails entirely.
Should you do it yourself?
Do it yourself for the cavity, conservatively, without forcing anything.
Get someone in if the door needs to come apart, because on an orphaned appliance that is the job where the downside is permanent. The Kleenmaid cooktop above is usually the same vintage.