Sensor location and permitted cleaning methods vary. A shiny strip inside one drum is not a universal guide to every dryer's components.
Understanding this situation
Residue can be relevant on models with owner-cleanable sensing surfaces, but scratching, solvents or abrasive tools can damage them. A drying result alone does not prove that the sensor needs cleaning or calibration.
A useful next step
Follow the exact manual with the machine safe and use only the approved method. Dry or refit parts as directed. If performance remains abnormal, arrange assessment rather than entering service menus or trying increasingly aggressive cleaners.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.