Diagnosis
Uneven heating between zones. The top heating element and fan are running hotter than the lower system, or airflow is blocked.
How to Fix It
Run a calibration test. With baskets empty, select BAKE, set both zones to 350°F, and run for 10 minutes. Use an oven thermometer in each basket. If temps differ by more than 25°F, the unit needs recalibration via service. For cooking, manually adjust: set top zone 25°F lower than the bottom zone, or swap basket positions halfway through.
If That Didn't Work
Check for obstructions. Remove both baskets and crisper plates. Look up into the top heating chamber. Ensure no large food debris is stuck on the upper heating element or blocking the fan guard.
Heads Up
This is a known design challenge with stacked baskets. The top basket is closer to the heat source. Always preheat for 3 minutes and use the recommended basket shaking for even results.