DIAGNOSIS The jar drive socket has jammed onto the drive coupler. Often caused by a hot blend or overtightening when placing the jar.
FIX Do not use tools on the jar. Hold the base firmly with one hand. Grasp the jar handle with your other hand and twist counter-clockwise with a sharp, jarring motion. A rubber jar opener pad can improve grip. The goal is to break the static friction, not muscle it.
IF THAT DIDN'T WORK Apply a few drops of isopropyl alcohol around the base of the jar where it meets the drive coupler. Wait a minute for it to wick in, then try the sharp twist again.
HEADS UP Never try to remove the jar while the base is still plugged in. Accidental activation causes severe injury.