DIAGNOSIS The "Brew Strength" control and 1-4 cup logic are not functioning optimally. For small batches, the machine may not deliver water at the correct rate or temperature.
FIX First, ensure you are activating the setting correctly. Add water for 1-4 cups. Press the "1-4 Cup" button; its light must be ON. Then press "Brew". The brew cycle will be slower. Use a medium grind, not fine. This setting uses a lower showerhead pressure.
IF THAT DIDN'T WORK The thermal probe that regulates temperature for small batches may be scaled or faulty. Descale the unit thoroughly. If the problem persists, the probe may need calibration or replacement.
HEADS UP The "1-4 Cup" and "Brew Strength" settings are independent. For best results with a small batch, use the 1-4 Cup setting AND the "Strong" brew setting.