I had the same issue when the filament snapped so I removed it manually. The machine was stuck trying to unload filament that wasn’t there. I was able to fix it by unplugging the AMS and force feeding the filament through the AMS and loaded the printer like it was from the side spool. After it was load, I plugged the AMS back in an hit unload and then it worked no issue. Seem if you pull the filament out without manually for whatever reason(snapped filament in my case) it can get stuck thinking there still filament in the AMS when there is none. I wish Bambu would add the ability to control the AMS motors like the hotend extruder motor just for situations like this.
Just a tip for anyone reading this in the future. If you have filament breaking frequently in the AMS then you need to dry your filament. I know it sounds like the opposite should be true but when filament absorbs moisture from the air it becomes very brittle and breaks easily.
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I used to leave filament in my old Anet A8 for months on end and would regularly find it snapped off within a foot or so of the extruder. My guess is that, as you say, it had absorbed moisture and gotten brittle. Not all brands did it but it was often enough that I just lived with it rather than freaking out. I’m kinda lazy.
The same thing happened to me, however, I cleared all the ptfe tubes and found nothing but still got the error and constant unload on spool 1. I was somehow able to trigger the spool to load and sure enough, I saw the new color pushing out a piece about 3 inches long of the old color. It seemed to have been caught in the section right after the motor under the AMS since I could watch it exit the AMS.
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THANK YOU, THANK YOU! THANK YOU! I’m a 70 yo woman and this made my life SO much simpler. Can’t express how thankful I am that you shared this information!
I had the same problem.
There was broken filament underneath the AMS
read this guide. Turn off power, remove PTE tube from back, use hex, take out the 2 screws holding the x4AMS feeder, lift up gently, remove the 2 connectors, and you can easily see the filament in the PTE tube.
If bamboo were smart, they’d let us post pics, videos, and links, but since they aren’t…
on youtube search " Bambu lab AMS clog fix tutorial, failed to pull out the filament from the extruder issue" and you’ll see a video by SavageLau.
also search this for bambu wiki for “Replacing the AMS Internal Hub Unit and AMS Internal Hub Motor”.
And bambu…fix your stupid website.
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Welcome to the forum!
Once you satisfy the requirements of a new user. Then you will become a basic user.
You can then upload pics, videos and 3mf files as you like.
It’s a bot and scam thing to protect the site.
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I cleared the filament from the AMS like so many videos show, but I still had the same issue (red lights for one spool double-flashing red). Finally I realized a small piece of filament was also stuck in the junction right before the filament exits the AMS. I found this video that shows how to remove filament stuck in the junction, though I found it worked better pushing the filament out the other direction from what the video shows (at least in my case).
https://youtu.be/VOJpSw6mbl0?t=186 (start around 3 minutes in)
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I also had nothing stuck and after many hours and a complete teardown of the AMS I found one of the filament sensor switches stuck down (Simulating stuck filament) I was able to free it up but have ordered a replacement part for the next time it happens. Will attempt to upload picture.
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Sorry for some reason it wont let me post a picture but this sensor/switch it in the combiner section 4 into 1.
I ran into a problem with my AMS today. Some Bambu ASA snapped and somehow during the course of retracting managed to flip up one of the magnets inside the internal hub. No idea how.
This meant the filament was getting blocked from going out. When I took it apart (which is a tedious process) I saw the magnet standing taller than the others. It was turned upward, not laying like the other three.
Reassembling the internal hub is a chore. The only way to keep the magnets in place is to use a stack of two other magnets on the top side of the shell to attract them. This pulls the guide magnets in and lets you get the PCB back onto them. Otherwise their own magnetism draws them toward each other and they jump out of the slots.
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