Stratasys J850 Manual page 101

When the Maintenance Counters screen opens, scroll down to the General
Pumps section.
The waste-pump tubes that require replacing are displayed in red.
To replace pump tubes, you replace the "cassette" assembly that attaches to
the pump in the printer. Replacement cassettes are supplied in the printer
Start-up Kit. Additional cassettes can be ordered from your Stratasys service
provider.
1. Make sure that the printer is in Idle mode (see the figure on page 4-4).
2. Using an 8-mm hex (Allen) key, open the two latches that secure the left
printer panel (as you face the printer).