A method for measuring the moment of inertia of a washing machine drum containing a load. A fan system of this type reduces the fan inefficiency caused when one fan in a series mounted pair is not operating, either because it is free-wheeling or in a locked rotor condition. Upon rotation of the barrel, the impeller vanes function to supercharge the fluid supplied to the piston bores. The overhead vapor is condensed to produce an overhead liquid of lubricant boiling range hydrocarbons, a portion of which is recovered as a product and a portion of which is recycled. The first and second sections of the twisted string are on a first side and second side, respectively, of the cord guide. The system architecture preferably includes a microprocessor for controlling the overall system operation.