AMS stuck in unload loop

machine has been working flawlessly including the ams till today.

went to change a roll of filament and pulled out the old and put the new in.

Now for some reason the ams thinks that slot is loaded but it not.

There is absolutely nothing stuck in the PTFE or buffer, etc.

I cannot reset the AMS or clear that slot and its stuck in this never ending loop.

I have seen other posts about this and people saying to tear the machine a part but I know for a fact there is nothing stuck and the entire track … because all of the prior filament was unloaded.

Anyone know how to solve this? I opened a ticket but responses from bambu lab are sub par to the say the least so I don’t have much faith in getting this resovled anytime soon.


Did you try turning the machine off completely and rebooting? Maybe disconnect and reconnect the AMS to the printer?

If you haven’t it might be worth a shot. Maybe even unplug the machine and let it sit without any power for 15-20 min?

Might not fix anything but you never know.

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I am at hour two now… I the user only changed the roll of filament and now the AMS is stuck is this unload current filament loop.

I have tore everything a part and there is nothing stuck in any of the PTFE or hotend.

I did a factory reset but that is only for the X1C and the Reset AMS does nothing or at least what I think it should do it does not.

I will disconnect power for a while but I believe the AMS is dead stuck in a use case they have not thought of… not sure why seems one would think of this use case or at a minimum give the user the ability to totally reset the AMS.

There are at least 2 filament present switches in the path from AMS to extruder. One is right at the top, it’s triggered when you first insert filament into the top of the drive unit thing. The other is in the hub on the underside of the AMS. There may be one in the extruder, I’ve not looked into it.
I wonder if a bit of debris has caused to magnet in the hub switch to stick. You can see the inner workings here, Dismantling and cleaning the AMS filaments hub | Bambu Lab Wiki
The magnets that you are cautioned to pay attention to are pushed by filament as it passes through the hub. If one is stuck, it will report that retract needs to continue. I would try disconnecting the AMS from the buffer and pushing a clean piece of filament through the tube and into the hub to see if the magnet can be bumped back into place. Or use the handle end of a screwdriver to tap on the hub. Don’t whack it, just tap it to try to knock the magnet back.
If it’s the switch in the upper drive unit that’s stuck, I have not looked into that yet.

Edit: Found this page, it might be helpful,

Edit 2: This may also be helpful,

I keep finding stuff so I’ll post a link to the top page that has the above and more,


did you ever get this resolved I have the exact same problem. My wife pulled the filament out and now it is stuck in a loop where I can not use the machine because it thinks there is something stuck somewhere and there is nothing.

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did you or @fgs536 ever get this resolved? running into the same issue, not really sure what to do

This just happened to me, no idea how to fix it

The issue I had was indeed broken filament within the AMS tubes. I had to take mine apart and remove the filament and then the issue was resolved for me.


Bambu rearranged the wiki and added a bunch since my last post. Here is the link to AMS trouble shooting. You will probably have to look at each one as none are titles unload loop.

@jacobdorsey @fgs536 it was broken filament for me as well. Seems extremely unlikely given that it was two slots simultaneously and during my side spool filament change but that was what caused it. Take apart the AMS and look at the PTFE tubes going into each of the slots, takes like 5 minutes.

Ah, I found a 5 inch length of broken filament in the tube! Thank you


I am having a similar issue.

I am having a similar issue. I did initially have filament stuck inside slot 1, it was I’m the internal PTFE tube on the underside of the AMS unit.

I removed the stuck filament, when I turn it back on without any filament inside slot 1 the red light is on. I tried loading in filament, and it won’t start gripping it when I click the button in the Bambu Handy app or from the computer.

it immediately starts retracting the filament, even whatever I pushed inside the tube and just keep spinning backwards then it tells me that there’s filament stuck inside and it’s on an endless loop.

Its the same thing for me. did you found a solution for this in the meanwhile?

Same problem here, no filament anywhere. I cant use the machine now.

I had the same problem on the X1C+AMS, it was caused by a small piece of chewed up filament stuck in the extruder, stopping the filament detection switch from working.

On the Bambu Lab wiki, search for:

HMS_0700_2000_0002_0004: The AMS slot1’s filament may be broken in the tool head

This helped me resolve my issue.

If the issue occurs after you opened the filament buffer. Maybe it caused by the magnet is in the wrong position. There is a red mark on one side of magnet, it should point to the sprint when installing.

Welllll… I did find a piece of filament, so the error was correct.

Thank you for the posts this pointed me in the right direction which was that there was filament stuck in the AMS. “The Edge of Tech” does a YouTube Video on fixing this. Search for: “How To Clear Broken Filament Jam From A Bambu Lab AMS (It’s Easy!)”. It Takes about 10 mins

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I also had a filament stuck in the AMS. The filament broken in many places and removing most were easy by following the youtube videos either from Bambu Lab or other people. But one piece was stuck in the bottom of AMS. The bottom of AMS has a junction point were all 4 bowden tubes meet. I could see the end of the filament, but it was inside the junction point. I ended up using an alignkey to push the filament out. Keep in mind you will need to press down on the latch at the top of the junction point to allow the filament to move. I started with a 3 MM alignkey and then used a 2.5 MM alignkey. I’m so happy that I didn’t have to disassemble the junction point.

Same problem… I followed all the instruction, clean all the ptfe pipe, dismantle all the part… I found small piece of filament. But the printer load the filement to the head… but the error message is the same…

Any idea?