Xerox 7700DX - Phaser Color Laser Printer Service Manual page 246

Note As the main drive assembly is being installed into
position, make sure the gears are meshed with the
mating gears by slightly rotating the main motor until the
main motor bracket seats without stress, and flat against
the frame. Rotate the main drive after installing the
assembly to ensure it rotates freely, and ensure it is FLAT
against the frame. It is easy to pinch or short wires under
the main drive assembly bracket.
Make sure that the red Bias Transfer Roller wire is
connected near the right side of the main drive assembly
to its mating connector on the frame.
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Phaser 7700 Color Laser Printer Service Manual