Microwave runs but food heats unevenly; some areas are very hot while others are cold.

Safety first: Use only microwave-safe cookware and avoid metal.

Step-by-step checks:

• 1. Verify turntable rotation: Ensure the glass tray rotates smoothly during operation.
• 2. Check load size: Avoid overcrowding the cavity; arrange food evenly on the tray.
• 3. Stirrer inspection: On some Grundig models, a stirrer fan behind a ceiling cover distributes microwaves. If the cover is warped or the fan is jammed, heating will be uneven. Inspect and clean this area if accessible.

If mechanical systems are working and cookware is appropriate, some unevenness is normal, but severe issues may indicate a failing magnetron or waveguide problem requiring professional diagnosis.