Relate it to cooking
Include whether food heats normally, slowly or excessively and whether a displayed temperature is a setting or a measured reading. Do not infer a thermostat fault from a lamp alone.
Keep settings comparable
Record the programme and selected temperature used for a familiar result. Assessment can consider controls, indication and actual heating together without relying on an unverified kitchen thermometer reading.
A useful distinction
The indicator may cycle as part of normal regulation, depending on the model. A changed cooking result gives the behaviour context and prevents an enquiry relying solely on the duration of a light.