Failed To Pull Back Filament Error

I’ve emailed support but not gotten any response yet so thought I’d pick the community’s brains. After almost every print, regardless of if I’m using the AMS Lite or a single spool I get this error:


When I remove the print head there’s about 30mm of filament still inside it with a bit sticking out the top.

I get this issue regardless of type or brand of filament. When I try retry it throws the same error and the system freezes, the only way to get out of the error is to power off power on the whole print.
Anyone have any suggestions?

Do you know what firmware version you are on? If you’re not upgraded yet, might be worth it? I’d be surprised if this were firmware, but might be worth upgrading to see if it might help.

Beyond that, does manually unloading filaments work? So like power on/off, and then go into the filaments menu and try unloading a loaded filament.

Oh also, do you know if you get these errors when you have multi color prints? It also retracts filaments when it changes colors if I recall correctly.

My line of thought is trying to figure out if this is a hardware or a software problem; if neither of the above work than it might suggest some issue a sensor - though far from a 100% confirmation.

The picture with filament sticking out the top is where it cuts the filament
and you can pull the filament out manually and then hit retry i found this happens with the single spool as it doesnt have the ams help to rewind it far enough , if its also happening with the ams check the ptf tubes and the tightness of the angle in which they are attatched

Once it fails to auto unload at the end of the print, manual unload doesn’t work.

I haven’t done a bunch of multi color, but when I have it has changed colors without the issue.

Here’s my thought on this, it cuts the filament, and retracts up the tube back to the AMS, but it’s not purging that piece that’s still in the print head. It’s not doing anything with it, it just sits there and clogs the system…

It cuts the filament, it doesnt need to purge unless you are changing filament or colour, manually needs a little user input,then it is replaced, besides that it can only purge if it has assistance if there is nothing to push the filament through then it cant , be it the ams and hotend extruder gears or just the extruder gears *or you choose to heat the hot end up remove it manually *

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If it’s at the end of the print, doesn’t it need to purge the cut piece from the print head? That error message reads that the issue is filament stuck in the head. It’s almost like it’s cutting it, pulling back the rest, and then seeing what’s in the head as an error…or am I losing my mind? If I pull the head, yank that little “tail” of filament out, reinstall the head and then click Retry…the error clears, so to me, that piece does need to purge since it appears that’s what is causing the issue.

https://wiki.bambulab.com/en/a1/manual/intro-a1
Filament hub and filament sensor
I believe what you are refering to is the hotend which is a part of the printhead
If you look at the filament hub which is also part of the printhead , it sits just above the the extrusion gears and will require a little manual winding of the spool to remove it from the printhead (toolhead)
A1 Series Extruder Module installation tutorial | Bambu Lab Wiki *

*changed link

Hai, I just bought an A1 2 months ago and had been seeing this problem as well. Had you found a solution for it? I had to yank out that piece of filament as well everytime when it had the problem and it would be resolved.

I’m having the same issue. I’ve had the printer for a month and a half (no ams lite) and it’s worked great. Today it started doing this every time I unload a filament. I’ve tried multiple filaments of PLA and PETG. I don’t know what changed to make the problem start.

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Hey everyone,

I recently ran into an issue with my A1 where the AMS wasn’t detecting filament correctly—and I managed to find the cause, so I’m sharing in case it helps someone else.

As eecharlie mentioned , the problem turned out to be the lever mechanism, but more precisely, it was the tiny magnet attached to the lever arm.

Here’s what’s going on:
There’s a Hall sensor on the small board (see attached image), and it reacts to a magnet embedded in the lever. When filament is inserted, the lever moves and brings the magnet closer to the sensor, which then registers filament presence.

In my case, the magnet had come loose from its slot on the lever. It was still inside the AMS and sticking to the lever, but not positioned correctly, so the sensor wasn’t being triggered.

Here’s what I did:

  1. Sanity check: I used a small spare magnet to test whether the sensor was working. You can check this by going into the Control icon on the printer and looking at the green dot on the extruder icon. That indicator will change when the sensor is triggered.
  2. Repaired the magnet placement:
    To fix the magnet back in its proper place, I first removed the tiny spring from the interior wall where it’s latched. Then I carefully removed the pin holding both the lever arm and the magnet, took out the arm, and placed the spring somewhere safe—you do not want to lose this spring, as it’s likely impossible to replace.

Once the arm was out, I removed the magnet (it was just loosely sticking to the arm), then applied a bit of superglue activator to the magnet slot on the arm. Using tweezers, I dabbed a tiny amount of CA glue to the side of the magnet that still had glue residue, placed it back into its slot, and held it in position for a few minutes. After that, I reassembled everything and tested the Hall sensor again—before fully screwing everything back together.

And voilà—that fixed it for me!

It’s a bit fiddly because the magnet is really tiny, but totally doable.

Hope this helps someone down the line!