DIAGNOSIS The silicone gasket (sealing ring) on the blade assembly is damaged, missing, or misaligned.
FIX Unplug and disassemble the pitcher. Remove the blade assembly from the pitcher base. Peel off the clear silicone ring. Clean the groove thoroughly. Ensure the new or existing ring is seated perfectly in its channel without twists. Reassemble tightly.
IF THAT DIDN'T WORK Check the pitcher itself for hairline cracks, especially around the center post where the blade assembly locks in. A cracked pitcher must be replaced.
HEADS UP Always hand-wash the gasket and blade assembly. Dishwasher heat warps and degrades the silicone.