Xerox Phaser 8400 Service Manual page 51

The level of the ink in the reservoir is kept at a constant level. If the pressure purge
tubing is pinched, the Printhead may not purge properly. In addition, because the
purge tubing also acts as a vent to atmosphere when not purging, a more serious
failure may occur if the ink overfills because the reservoir is not allowed to vent
properly.
Warning
When servicing the printer be careful of the Purge System as it passes the
Printhead. If a damaged wiper blade of the Purge System catches on the
Printhead, it could propel hot liquid ink upward into your face.
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