Hoover Shampoo- Polisher Owner's Manual page 21

Servicing of Double Insulated
This appliance is double insulated. In a double-insulated appliance, two
systems of insulation are provided instead of grounding. No grounding
means is provided on a double-insulated appliance, nor should a means
for grounding be added. Servicing a double-insulated appliance requires
extreme care and knowledge of the system, and should be done only by
qualified service personnel. Replacement parts must be identical to
those parts being replaced. A double-insulated appliance is marked with
the words 'DOUBLE-INSULATION- or 'DOUBLE INSULATED. The symbol
Lubrication
The motor is equipped with two sleeve bearings. These bearings contain
sufficient lubrication for the life of the motor. The addition of lubricant
could cause damage. Therefore, do not add lubricant to either motor
bearing.
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