AMS Slot 3 does not retract filament

Hello all,

Since today my AMS does not manage to pull back the filament into slot 3.

When I start a multicolor print, everything runs as usual. At some point there is a change to slot 3 which also works fine.

As soon as it wants to pull back slot 3, it does not succeed. It is enough if I loosen a Bowden and pull or press very lightly on the filament, immediately the retraction works again.

What could be the reason for this?


Hi Shadow,
I had the same problem, as have many others, with slot 3.
Drying filament in a Filament Dryer makes a huge difference. Abrasive filaments and brittle filaments seem to be an issue. There must be something about the filament path of slot 3 that increases the risk of binding.


I have been printing ASA, ABS and PETG from extrudr for a little over a month now, all the time with no problems. Also the ngen of colorfabb worked wonderfully.

The problem occurred only now with PLA NX2 from extrudr. All rolls are the same, all plastic, etc.

I have tried a few things without success. Now I have once exchanged roll 3 with roll 4. It worked a few times until then once slot 4 made problems. At the moment this slot works again.

So it could be the filament, the roll itself is identical to the others because the same manufacturer.
I will dry the roll with the drying function of the X1 Carbon, let’s see if that brings something.

My X1c is 3 days old, used slot 3 once and on the second print it did this

After taking apart the AMS, pulling out the filament ( and adding some more bends and unwinds to it ) I moved the same filament to slot 2 and its printing just fine. I don’t think its the filament. If you look on reddit there are MANY reports of the same thing with all kinds of recommendations from clogged hot end to filament to bad gcode to sun spots …

Ive submitted a ticket to support. My expectation is that a $1500 device should last and work well for 72 hours. If Bambu knows ( they should ) there is an issue with slot 3 then find it fix it and recall or send parts for self repair.

Quick question when the filament in slot three gets past the AMS and goes to the buffer where does it stop and retract?

When I pulled out the filament I pulled out about 3 or 4 feet of filament, if that helps

Im finishing the current project in another slot, when its done Ill retry slot 3.

Mines the same. 3 and 4 are so unreliable. I dont know where to start. When i wiggle the tube where enters the hub. Sometims helps. Most times its stuck and needs pulling quite hard to get out. Theres fixes out there but i dont know if they work

And btw 6 days later no response from support ticket

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