X1 Carbon + AMS load failure. Looking for next troubleshooting steps

Bambu Lab X Series Troubleshooting
1

I’m helping a friend troubleshoot his X1 Carbon that started having filament loading issues almost immediately after he bought it. He got frustrated with it and let it sit for a while, and unfortunately the warranty expired about two months ago. The printer only has 22 hours on it. It also needed a firmware update, so I completed that first.

Fortunately, I have my own functioning X1C, so I’ve been able to swap known-good parts for testing.

The printer originally had a major tension/resistance issue with the AMS2. Filament was very tight going through the AMS internal hub, and the internal hub release button was broken. I found a replacement design online and printed a new button that relieves the spring tension by about 5 mm. After installing that, filament passed through the AMS much more easily, and I thought that would solve the problem. It successfully loaded filament twice, but then the next issue appeared.

At first, the filament would load to about 1 inch from the printhead, then retract. It would repeat this a couple of times and then throw an error.

I then removed the PTFE tubing, squared up all the ends, and reamed them slightly. I also shortened the PTFE run, bypassed the 4-to-1 PTFE adapter, and straightened out some tighter bends in the tubing.

After that, the filament started loading all the way to the extruder. However, once it reached the extruder, the AMS2 would grind for a few seconds, then retract the filament. It would repeat this cycle a few times and then give error:

0700-7000-0002-0003 — “Failed to extrude the filament. Possible cause: extruder or nozzle filament.”

The strange part is that the filament actually does load into the extruder/hotend. To remove it afterward, I have to run the unload cycle or cut it with the cutter.

I thought maybe the filament load sensor was the issue, so I removed the upper PTFE tube and manually inserted a piece of filament into the extruder. The printer recognized the filament immediately, so the load sensor appears to be working.

Because the printer originally had issues with the AMS2, I still suspected the AMS was the most likely cause. I mounted an external spool and fed filament manually. It loaded and fed just fine, which further made me think the issue was still AMS-related.

To test that, I connected the AMS from my own working printer. Mine is an original AMS, not an AMS2. With my known-good AMS connected to this printer, I got the exact same failure as with the AMS2. It loads filament all the way to the extruder. This AMS does not grind the filament, but once the filament hits the extruder, it clicks a couple of times, retracts, repeats that cycle a few times, and then gives the same “Failed to extrude the filament” message.

I then swapped in the hotend from my working X1C. No improvement.

Next, I removed the extruder from the problem printer. It looked basically new, which makes sense given the printer only has 22 hours on it. I did not see ground-up filament dust, debris, damaged gears, or anything obviously wrong. Filament passes through it by hand without issue.

Finally, I swapped in the extruder from my functioning X1C, thinking that would solve it. It still has the exact same problem.

So at this point I believe I have ruled out:

  1. Firmware level — updated before testing

  2. AMS — tested both the original AMS2 and my known-good AMS1

  3. AMS odometer/feed motors — same issue with two different AMS units

  4. PTFE tubing/routing — squared/reamed ends, shortened path, removed tight bends, bypassed 4-to-1 adapter

  5. Filament load sensor — manually inserting filament is detected immediately

  6. Hotend — swapped in known-good hotend

  7. Extruder — swapped in known-good extruder

Current behavior:

  • Filament from AMS loads all the way to the extruder/hotend.

  • The printer then seems to fail the automatic AMS loading/extrusion handoff.

  • It retracts and repeats several times.

  • It then errors with 0700-7000-0002-0003: Failed to extrude the filament.

  • If the filament is left in place after the failed load, it appears to actually be in the extruder/hotend and can be unloaded/cut. It will also print just fine after restarting the printer.

  • External spool loading/feeding and printing works normally.

At this point I’m running out of ideas. Since the issue stays with this printer even when using a known-good AMS, known-good hotend, and known-good extruder, I’m wondering if the next place to look is the toolhead board, cutter, toolhead cable, or some firmware/control issue during the AMS handoff.

Has anyone seen this exact behavior before, where AMS loading gets filament all the way to the extruder but then retracts and reports “Failed to extrude,” even though the extruder and hotend are not clogged?

What should I check next? Is there a specific board, cable, cutter sensor, or calibration step involved in the AMS-to-extruder handoff that I may be missing?

Also, does anyone know whether Bambu will help with a case like this even though the warranty expired two months ago? The printer only has 22 hours on it and apparently had issues almost from the beginning. I feel bad because I recommended this printer to my friend after having a great experience with mine, and unfortunately his has been a dud so far.

2

What I find quite intriguing is the reason for presenting your entire post as a quote of someone’s else post.

As for Bambu’s help post warranty period, you may not be aware, but Bambu has proven time and again having issues assisting even those printers still under the warranty period…but you can always try. You may get lucky.

3

That was unintentional. I edited it so it’s not confusing. It’s unfortunate that Bambu is not better about standing behind their products.

4

Your printer is out of the warranty period, you say. In the EU, that period covers up to 2 years from the date of purchase on your invoice. In other parts of the world, Bambu offers only 12 months warranty, and in some more remote parts, not even that (not sure of the last bit, as info came from an user living in a more distant and remote geographical area, not in the EU, UK, US or in China’s regular distribution areal).

One option is for you to submit a ticket to their so called “customer support services “ , present your case and request their assistance. If they do decide to answer, they may decline assistance because of the lapsed warranty period, or they may suggest that you buy the components they may deem necessary for the repair. There’s no guarantee they will answer, and if they do, there’s definitely no guarantee that the components you will acquire from Bambu will solve your problems.

Another option would be to seek (online) and purchase a functional 2nd hand X1C, with the lowest print hours you can find, and you may use one or the other for spare parts. I’d suggest, if the second printer is functional, to use it as your main printer and keep the one you have as a source for spares. The good thing is that the prices for 2nd hand X1Cs have dropped quite significantly, and a good functional X1C with relatively low print hours could be found quite easily.

Your call.