A1 and A1 mini: not extruding or under-extruding (clogged nozzle, slipping extruder or nozzle too low)

Symptom

The A1 or A1 mini extrudes no filament or too little: the first layer comes out with almost no plastic, the extruder gear clicks and skips, or it turns but nothing comes out.

Likely causes, from most to least likely

1. Nozzle too close to the bed on the first layer: it barely lets plastic out.
2. Clogged hotend: the extruder clicks and skips.
3. The gear slips on the filament: filament that wears easily (such as PLA Aero), an incorrectly assembled extruder or a loose screw on the side of the toolhead.
4. Several filaments or a broken piece inside the AMS lite hub.
5. Worn extruder gear or missing teeth, or a motor that does not turn smoothly.
6. Settings asking for more than it can melt: temperature too low for the material or very high speed (Ludicrous mode).

Checks to tell which one it is

• Move the toolhead to the purge area and extrude from the screen: if it extrudes fine there, the problem is the first layer height.
• Remove the hotend, enable maintenance mode (Settings → Maintenance), set 170 °C and extrude: if the extruder pushes fine without the hotend, the clog is in the nozzle.
• With the printer off, cut the filament with the cutter, hold the idler bracket, pull the filament out and look for a chewed notch; try another spool.
• Move the filament by hand through the AMS lite hub to check for broken pieces.

Before you start

Before taking anything apart, cleaning or adjusting it, switch the printer off and unplug it, unless a step says otherwise, and do not touch the nozzle, the heater block or the bed until they have cooled down. If in any doubt about electricity, heat or moving parts, stop and ask a professional.

Step-by-step fix

1. If the nozzle is too low

   Run a full bed levelling from Calibration. If that does not help, with the hotend cold tighten the heater assembly screws, check that the lower part of the hotend has no play and that its buckle is properly latched.

   Check: The first layer has normal thickness and the nozzle does not rub the plate.

   If that does not fix it: Follow the Bambu Lab guide for an A1 series first layer that is too low.

2. Unclog the nozzle

   Raise the nozzle slightly above the filament's temperature (250 °C for PLA) and extrude from the screen; with TPU do not press load more than three times. If nothing comes out, wearing heat-resistant gloves, run the unclogging needle through the tip several times (it does not work for nozzles smaller than 0.4 mm) and extrude again.

   Check: The filament comes out straight and steady.

   If that does not fix it: Do the cold pull (next step).

3. Cold pull

   Heat to 100 °C (for PLA), remove the hotend while hot wearing gloves and pull the filament out of its inlet with pliers. Refit it, heat to 220 °C and load another colour of the same material; once only the new colour comes out, drop to 100 °C and pull it out. Repeat until it comes out clean and test extrusion.

   Check: Extrusion is back to normal.

   If that does not fix it: If it will not clear, replace the hotend with a new one.

4. If the gear slips

   Try another spool: if only one fails, it is the filament. If it slips with every spool and the hotend is clear, open the extruder using the A1 series extruder cleaning guide and check that the spring and metal cap are seated correctly and the screw on the side of the toolhead is tight.

   Check: The gear grips the filament and extrudes.

   If that does not fix it: If the yellow gear is worn or missing teeth, or the motor does not turn smoothly, it needs replacing.

5. Check the AMS lite hub

   Make sure there is not more than one filament in the hub and no broken pieces; take it apart if needed and move the filament by hand to confirm the path is clear.

   Check: The filament passes without catching.

   If that does not fix it: Contact Bambu Lab support.

Prevention

• Use the temperature from the material profile and avoid Ludicrous mode if you notice missing plastic.
• With PLA or PETG clean the nozzle and extruder gears every 5 spools; with carbon fibre filaments, every 2.
• Keep the tubes free of sharp bends and leave tangle detection switched on.

Still not fixed?

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Printers it applies to

The Bambu Lab A1 family: A1 and A1 mini.

Official sources

This guide summarises the official documentation linked here:

• A1 series printer extrusion abnormal troubleshooting · Bambu Lab
• A1/A1 mini Nozzle/Hotend Unclogging Procedure · Bambu Lab
• A1 Maintenance Guidelines · Bambu Lab
• How to Avoid Nozzle Clogs · Bambu Lab