DIAGNOSIS The motor is seized or jammed. The most common cause is a worn or stripped drive coupler connecting the motor to the blade assembly.
FIX Unplug the unit. Remove the pitcher and locate the black plastic drive coupler in the center of the motor base. Use a flathead screwdriver to pry it out. Inspect the square teeth. If they are rounded or cracked, replace the coupler. Part number is often CBJ-550-Coupler. Insert the new one flush.
IF THAT DIDN'T WORK The motor itself may have failed. Listen for a burning smell. Motor replacement is not cost-effective for this model.
HEADS UP Never force ingredients, especially frozen, with the tamper while the unit is running. This strips the coupler.