Small accessories can require a particular rack or locating arrangement. Their size alone does not ensure they will sit securely on ordinary shelf rails.
What the observation means
A tray can tilt when its contents shift or when it is pulled forward. Combining halves from different models may leave unsupported edges or incorrect spacing. The accessory instructions describe the intended loading and removal method.
A useful next step
Confirm the exact compatible parts before using them, and keep their weight limits in mind. If a tray rocks while cool and empty, do not fill it with hot liquid. Describe the support arrangement when seeking help instead of bending the tray or modifying the rails.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.