How do I know it is the AMS internal hub unit and not something else?

Rule out the cheap causes first: snapped or curled filament in the path, a spool that does not turn freely, wet brittle filament, and worn PTFE tubes. If filament reaches the hub and then grinds, stalls, or shows dents from gear slippage at that point, the internal hub unit is the likely failure. Worn PTFE is actually the most common AMS hardware failure, so check the tubes before ordering a hub.

How much does the AMS internal hub unit cost?

The official Bambu Lab store lists the AMS internal hub unit at 24.99 dollars. The same part is also sold on Amazon and by third-party suppliers like Micro Center and Partsbuilt, sometimes at a markup but with faster shipping.

Is replacing the AMS hub unit hard?

It is a medium difficulty repair. You are opening the AMS shell, disconnecting a couple of cables, swapping the hub assembly, and reassembling. No soldering, no calibration. The official wiki guide has the photos, but it assumes context it never explains, which is why this companion guide exists. Set aside an unhurried hour the first time.

Should I replace the PTFE tubes at the same time?

Yes. Worn PTFE tubing is the most common cause of AMS feed problems, and the tubes are cheap. If you already have the AMS open for a hub swap, replacing the PTFE at the same time costs a few dollars and rules out the other most likely failure in one session.

Bambu Lab Repair Help › AMS Internal Hub Unit Replacement

Bambu Lab AMS Internal Hub Unit Replacement: The Guide I Wish I Had

By Grayson Bryan, Third Party Services LLC · Published July 17, 2026

Disclosure: This article contains Amazon affiliate links. If you buy through them, Third Party Services LLC earns a small commission at no extra cost to you. It does not change what we recommend; every product here is one we bought or the exact part the repair calls for. Full details in our affiliate disclosure.

The short version

If your AMS grinds, clicks, or stalls when feeding and the filament path is clear, the internal hub unit is a prime suspect.
Check the PTFE tubes first. Worn PTFE is the most common AMS hardware failure and the cheapest fix.
The hub unit is an official 24.99 dollar part. The swap is a medium difficulty, screwdriver-only job.
The official wiki guide has the photos. This guide has the diagnosis, the shopping list, and the context the wiki skips.

How I got here

I run a Bambu Lab P2S with an AMS, and the AMS is the reason I bought into the ecosystem. Multi-color prints, automatic spool switching, filament kept dry. When it works, it is the best part of the machine.

Then it stopped feeding reliably. I opened a support ticket with Bambu Lab, described the symptoms, and the answer that came back pointed me to their wiki guide for replacing the AMS internal hub unit.

Fair enough. Except the wiki guide was harder to follow than it should be, the part was harder to source than a 25 dollar component has any right to be, and every search I ran trying to fill the gaps led to forum threads that ended in "did you ever fix this?" with no reply.

I got it sorted. This is the guide I wish I had found on day one: how to confirm the hub is actually your problem, exactly what to buy, and the swap in plain English.

First, make sure it is actually the hub

The AMS feeds filament in stages, and a "feed failed" style error can come from any of them. The stages are the first-stage feeder where the spool sits, the buffer and internal hub where four filament paths merge into one, and the extruder up on the toolhead. Grabbing a hub unit because a forum post said so is how people spend money on the wrong part.

Work through this checklist before ordering anything:

Look for broken filament in the path. A snapped segment stuck in a tube is the fastest failure to find and costs nothing to fix. Pull each slot's filament back and inspect the tip. A mushroomed or curled tip tells its own story.
Confirm the spool turns freely. Cardboard spools without adapter rings, or a spool rubbing the AMS shell, will fight the feeder motor and mimic a mechanical failure.
Rule out wet filament. Brittle, waterlogged filament snaps during retraction and jams the works. If your filament snaps when you bend it, dry it before blaming the hardware.
Inspect the PTFE tubes. This is the big one. Worn PTFE tubing is the most common AMS hardware failure, full stop. Look for visible grooves, ovaled openings, and drag when you push filament through by hand. Tubes are cheap and replacing them is easy.
Now look at the hub. If filament reliably reaches the hub and then grinds, clicks, or stalls, or you see dents pressed into the filament from gear slippage at the hub, the internal hub unit is your likely failure. That grinding sound with no forward motion is the classic sign.

Quick sanity check: the AMS has a surprising number of "fixed by a reboot" faults. Unplug the AMS from the printer, wait a few seconds, and plug it back in before you diagnose anything mechanical. It costs you thirty seconds.

The shopping list

Here is everything the repair uses. The hub is the only required purchase; the rest is what I would put on the bench with it.

Item	Why	Where
AMS Internal Hub Unit	The replacement part itself. Official list price is $24.99 at the Bambu Lab store; the Amazon listing ships faster in many regions.	Amazon
PTFE tube kit (2.5mm ID / 4mm OD)	Replace the tubes while the AMS is open. Worn PTFE is the most common feed failure and the tubes cost a few dollars.	Amazon
Fanttik E1 Max electric screwdriver	The driver on my bench. Any decent screwdriver set works, but the AMS shell has enough screws that powered driving with a light touch is a quality of life upgrade.	Amazon
Silk PLA for the victory print	Optional, but you will want a satisfying test print when it is back together. ERYONE's liquid gold silk is what I reach for.	Amazon

Prices and availability change; check the listing. The hub unit is also sold by the official Bambu Lab store, Micro Center, and Partsbuilt if you prefer to skip Amazon.

The swap, step by step

Keep the official wiki page open next to this. Bambu's guide for the filament hub replacement has the photos and the screw-by-screw detail; what follows is the plain-English narration and the gotchas it does not spell out. Search the Bambu Lab wiki for "replace filament hub" for your model, or start from the maintenance section for the X1 series, which covers the AMS hub procedure.

Step 1

Unload everything and power down

Unload all four slots from the printer side so no filament is engaged anywhere in the path, then power the printer off and unplug the AMS cable from the printer. Take the spools out. You want the AMS empty, disconnected, and on a table with good light, not balanced on top of the printer.

Step 2

Open the AMS shell

The top cover and shell come off with screws, and there are more of them than you expect. Go slow, keep the screws organized by where they came from, and do not force anything. If a panel is resisting, you missed a screw, not a clip. A muffin tin or a strip of tape to hold screws in order saves real frustration on reassembly.

Step 3

Photograph, then disconnect

Before you unplug a single connector, take photos from every angle. The hub connects to the AMS electronics and to the four PTFE paths, and your photos are your reassembly map. Then disconnect the cabling from the hub and free the PTFE fittings. The connectors are small and positively seated. Pull on connector bodies, never on wires.

Step 4

Swap the hub

Unscrew the old hub unit, lift it out, and set the new one in exactly the same orientation. Compare old and new side by side first. While it is out, look at the old hub's gears: if you can see wear, glazing, or debris in the gear teeth, you have your confirmation the diagnosis was right.

Step 5

New PTFE while you are in there

This is the moment to replace the internal PTFE tubes. Cut replacements to match the old lengths exactly, with clean square ends. An angled or ragged cut on a PTFE tube creates a lip that filament tips catch on, which is the same jam you are here to fix.

Step 6

Reassemble and feed test

Work your photo trail backwards: connectors, fittings, shell, screws. Reconnect the AMS, power up, and load one slot at a time, listening at the hub as each one feeds. Smooth, quiet feeding on all four slots is the pass condition. Then run a real multi-slot print, because filament switching is where a marginal assembly shows itself.

If the grinding continues after the swap: stop feeding and reopen the diagnosis. A new hub does not fix worn first-stage feeder gears, a failing hub motor, or extruder-side problems. Grinding that survives a hub replacement means the failure is upstream or downstream of the hub, and repeatedly retrying will chew up filament and gears.

What I would tell you after doing it

The diagnosis is the repair. The physical swap is screws and connectors. Confirming the hub was the actual failure is the part that separates a 25 dollar fix from a pile of parts that did not help.
Do the PTFE at the same time. It is the most common failure anyway, and the marginal cost while the AMS is open is a few dollars and ten minutes.
Photograph more than you think you need. Every connector, every cable route, before it comes apart. Future you, holding a shell and six screws of unknown origin, will be grateful.
Budget an unhurried hour. Someone comfortable inside machines will beat that. If it is your first time opening the AMS, rushing is how connectors get broken.

Not sure the hub is your problem?

Describe your symptoms and we will tell you what they point to before you spend a dollar on parts. We run this machine, we have done this repair, and the diagnosis costs nothing.

Get a Free Diagnosis

Quick answers

How do I know it is the hub and not something else?

Rule out the cheap causes first: broken filament in the path, a binding spool, wet filament, and worn PTFE tubes. If filament reaches the hub and then grinds, stalls, or comes back with gear-slip dents, the hub is the likely failure.

How much does the part cost?

The official Bambu Lab store lists the AMS internal hub unit at $24.99. Amazon and third-party suppliers carry the same part, sometimes at a markup with faster shipping.

How hard is the swap?

Medium. Screwdriver only, no soldering, no calibration afterward. The shell disassembly and the small connectors are the fiddly parts. Give it an unhurried hour the first time.

Should I replace the PTFE tubes too?

Yes. Worn PTFE is the most common AMS feed failure, the tubes are cheap, and the AMS is already open. Doing both in one session rules out the two most likely culprits at once.

More Bambu Lab repair guides are on the way, starting with the full AMS feeding diagnostic decision tree. The hub for all of it is our Bambu Lab repair help page.