Work through this in order — it's cheapest-first, and the top two items are the answer most of the time.
- Nozzle blocked. Debris and resin build up at the tip. Remove and clear it. This is the most common cause by a wide margin.
- Line kinked or disconnected. Follow the whole run; check where it flexes with gantry movement, which is where kinks form.
- Pump inlet filter clogged with dust. Easy to forget it exists.
- Valve left closed — if you fitted an inline valve for acrylic work, check you reopened it.
- Pump power and control. Confirm the pump is powered and that air assist is enabled in software for the layer you're running. A per-layer setting off is not a hardware fault.
- Pump itself. Disconnect the line at the pump outlet and feel for flow. Flow at the pump but not at the nozzle means the blockage is downstream.
Why it matters immediately
No airflow means smoke sits in the beam path, so cuts that worked yesterday stop going through today — the symptom looks exactly like power loss. Don't chase settings until airflow is confirmed.
LaserPecker publish their own documentation on this topic — worth reading alongside these community notes.
Official article