How do you replace the coupling on Waring Blender RSMB80WS?

To replace the coupling on a Waring Blender RSMB80WS, first, unplug the blender for safety. Remove the jar and the blade assembly from the base. Use a wrench to unscrew the old coupling from the motor shaft, then install the new coupling by screwing it onto the shaft securely. Reassemble the blade assembly and jar, and ensure everything is properly fitted before plugging the blender back in.