‘Head Not Ready’ means your printer isn’t detecting fluid flow or pressure stability. Here’s what to check before calling support.
What this fault means
This message appears when the CM750’s printhead can’t safely initialise ink flow—usually due to a fluid, valve, or pressure fault.
Primary causes & actions
| Cause | Fix |
|---|---|
| Ink tank empty or airlocked | Refill ink and run Fill Mixer |
| Pump not delivering pressure | Listen for pump activation; replace if silent |
| Valve 4 or 5 stuck closed | Test valves via Diagnostics > Valve Test |
| Faulty head pressure sensor | Inspect sensor connection or replace part |
How to resolve the issue
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Refill ink and makeup tanks
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Run Fill Mixer or Umbilical Purge
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Navigate to
System > Maintenance > Diagnostics -
Test pump and valve operation
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Reboot printer and test ink flow start
Preventing future problems
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Replace filters regularly
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Don’t power off during startup or shutdown
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Store printer properly if offline for more than 48 hours