AMS Lite Slot 4 Not Retracting

Anyone know why slot 4 on my AMS will feed filament but not retract? I checked and filament is not stuck, it easily moves by hand. It does this straight out of the box, I have never successfully retracted on slot 4, but the other 3 slots work as expected.

I am also getting errors that the motor is overloaded. when I push very gently on the filament funnel plunger and compress the spring ever so slightly, the filament successfully retracts. It’s as if the spring is putting so much force on the gears that the motor cannot overcome the force. However when I compare the spring force and filament resistance when I pull on it to the other feeder units, it feels the same. I have taken apart the feeder unit and ensured the gears are in the correct positions per the BBL Wiki. The spring looks intact and positioned correctly. I am using Bambu PLA basic, and have tried swapping spools around with the same results. Any thoughts?

Here is what the gears are doing when it tries to retract: https://youtu.be/TfazmGB6InI?si=TDa_HF5QNpXyEgcb

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Do a Ticket at the Bambu Lab support.

I have. I’m just trying to do what troubleshooting I can while it’s still the weekend. I’ve heard they can take days at a time to respond

Do the motors still run when the AMS tries to reel filament, if that’s the case you have to just replace spring mechanism that grips the roll, because it may have broke.
If motor doesn’t work then you have to replace the motor, there is no way around it if this is the case.
Here is a model that may help if the spring mechanism that holds the filament roll is broken, hope it helps.

Glad if this helps with your problem. :wink: :star_struck: :blush:

The motor does run if I release the tension on the spring. But once I let it tension again it stops. So the motor runs but it’s acting as if there is not enough torque

Well I can’t help ya nay further, maybe use the model I gave you.

I swapped the spool holders on slots 2 and 4, so I eliminated that as a possibility already. Thank you for the suggestions, though

No prob hope you find the solution, cannot help you any further.

Update: Bambu Lab support just replied to me and said it’s a known mechanical issue. They are replacing the right feeder unit.

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Yay good for you, luckily I have never seen or heard of anyone else having this issue. But please bear in mind I do not have AMS lite unit even though I got A1 mini. So I am only specialist when looking at on paper stuff, but have no experience at all.