National Vacuum Equipment 607 challenger series Replacement And Rebuild Manual page 13

13� Inspect the housing for wear or damage� If the housing needs
to be bored or honed, remove only as much material as is
necessary to give a smooth clean bore�
The maximum overbore we recommend is 0�060 inches� A new
housing has a bore of 7�875 inches�
If you bore or hone the housing, remove all connected accessories,
including the fan shroud, 4-way valve, gaskets, etc�
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12� Remove the four-way
assembly, gaskets, and check
valve assembly� Carefully turn
the housing upside down so
that the pump feet are facing
the ceiling�
14� Clean the housing of any
debris and apply a liberal
amount of lubrication to the
housing bore�
15� (Optional) If there is damage
evident to the bearings, they
will need to be replaced� Once
the rotor is removed, start
by cutting off the old bearing
inner race on both ends of the
rotor� Be sure to line up the
cutting wheel with one of the
vane slots so as not to dam-
age the rotor or seal sleeve�
607 Challenger Series | 13