So my A1 is brand new out of the box and is erroring. Here are the following errors:
https://wiki.bambulab.com/en/x1/troubleshooting/hmscode/07FF_2000_0002_0004
The green dot in the following image indicates that there’s filament in the extruder. I have taken apart the 4 way AMS hub and there’s no broken filament in there at all.
Sounds like your machine tried to pull back the filament and it broke off in the extruder that is inside the toolhead. Not the 4way hub.
I would be looking in the extruder for a broken piece of filament.
Are there visual instructions for disassembling it? I seem to only be able to find X1 or P1 guides.
You are right and I don’t own an A1 to know exactly what to do with that extruder. But there should be someone who will step up to help you disassemble the extruder.
The a1 mini uses the same toolhead: link
In this video there is a “proper way” to pop the hub off:
I had a similar problem. I also had the filament break in the tube. Check that
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Just finished taking it all apart and putting it back together according to this page: A1 series extruder cleaning tutorial | Bambu Lab Wiki
There’s literally nothing broken or dirty in the extruder. The only thing I saw was the left over red from my last print in the nozzle/heat block where it was cut (this is normal).
Edit: I just ran a 2 color print and it failed to color switch from black to white even though the filament has been pulled out all the way just fine. I got the following error: HMS_0700_2000_0002_0004: The AMS slot1's filament may be broken in the tool head | Bambu Lab Wiki
Is the green light still on in Bambu Studio? If it is not, maybe the switch was stuck open as if there was filament still there. I have had this happen to me. Still on the same extruder 2000hrs later.
It’s shown on the printer screen as on (green), yes. But that’s the problem, there’s no filament in there.
Sorry! I’m out of suggestions. I wish i could have helped.
That’s ok, maybe someone will know what’s going on with it. I put in a support ticket a couple of days ago as well.
Ticket is a good idea. For me it sounds like the hall sensor (filament detection) is damaged. If there is no filament at the sensor but still showing that there is something, it must be a sensor defect. And there is no filament, because you removed it from extruder and hotend.
The last try … maybe … try to disconnect and reconnect the sensor. Last time this helps me.
Do you mean disconnect the sensor board wire and back again, or to unscrew the board and rescrew?
Yes, only unplug and plug in again the
That was the solution for me. Weird Bambu plug 
How do you get to the cable though? I can’t find any instructions on disassembling that far down that leads to the cable.
Hi Eleos. I found this assembly/disassembly video in the wiki that may be useful for doing a strip down:
https://wiki.bambulab.com/en/a1-mini/maintenance/a1-extruder#assemblydisassembly-video
Thank you for that, helps with the cutter disassembly. Unfortunately it doesn’t cover the area for where the sensor cable is connected to.
The A1 and the A1 mini uses a different printhead then the core XY printers.
I found it here, it’s behind the control board in the back: A1 series toolhead Installation Tutorial | Bambu Lab Wiki
