Stratasys J850 Manual page 100

The tubes that pump waste material from the roller waste collector and the
purge unit should be replaced after 1500 hours of printing. At this time, a
counter should display a maintenance message on the printer interface
screen.
You can verify that the pump tubes need to be replaced by examining the
waste pump maintenance counters.
➢ Click on the "Maintenance Required" indicator.
or—
➢ From the Options menu, select .