I’m trying to troubleshoot a hardware issue on my Bambu Lab A1 Mini Combo 3D printer and would appreciate any guidance.

Hardware reference (for clarity): Bambu Lab A1 Mini Combo 3D printer

Issue description:

During prints, especially at higher speeds or when more filament is needed, the extruder begins to click repeatedly and the filament feed becomes inconsistent. This often results in under-extrusion or gaps in the print. The printer pauses or slows unexpectedly as well.

What I have checked so far:

• Filament spool tension and re-feeding
• Nozzle temperature settings
• Cleaned the nozzle and heat break
• Verified filament is not tangled

At this point I’m trying to determine whether this is likely due to a mechanical feed problem (gears, tensioner, idler), a drive motor issue, or a sensor/stepper calibration issue.

Specifically, I’m interested in:

• Common mechanical causes of clicking extrusion on this or similar models
• How to inspect the extruder gears and tension assembly safely
• Any recommended checks for stepper motor performance or idler alignment

Thanks in advance for any repair/inspection advice — I’m trying to identify whether this is a hardware fault or a setup calibration issue.

⟐ Answered February 09, 2026 at 22:08 MST

⟐ Commented January 23, 2026 at 20:31 MST

⟐ Answered January 23, 2026 at 9:55 MST

Hey there! I have a Prusa i3 mk3 that I've been using for quite a while now- at least a couple of years. Iirc, it has about 50+ hours of print time. For context, I am pretty experienced with these 3d printers and have a couple of years of fixing things in general. I also have all of the basic tools any good repair person would need: a soldering iron, multimeter, plenty of screwdriver bits, pry tools, etc.

Just recently, I was running a calibration when the printer suddenly restarted itself. I went to check it, and physically, nothing looked wrong. So, I decided to run the calibration again, and the same thing happened. This time, I noticed that it only happened after the hotend (the thing that heats the filament) was turned on. After manually turning on the hotend, I confirmed that it was the problem.

I found a guide on how to replace the hotend and followed it so I could get the part out. Throughout the guide, I didn't find anything wrong. There were no blown parts on the Einsy board, the wires weren't cut or crimped, and they were plugged into the right ports.

After finally getting the hotend off, it didn't seem like anything was wrong. For reference, the only things that go to the hotend are the heating element wires and a thermosister to check the temperature. The metal block looked good, and the heat sync looked perfect. There was only 1 thing I noticed that could be weird. The heater wires at the hotend kind of looked like they were touching, which could have been shorting, but they were stuck in their place when built, so nothing could have moved to suddenly short the printer. I wish I knew exactly how it heated the block, but that seems like it probably isn't the problem.

I then unplugged the heating element and not the thermosister, set it to turn on, and it didn't immediately restart. This tells me it isn't a software issue with the thermosister saying that the printer is overheating (again, the printer would restart as soon as the temp was set, not after a few seconds of heating).

My main (and honestly only) suspect at this point is the power supply failing. Is there a way to check if a power supply is failing or not? Or is there something else I should check/do that I haven't done? I want to make sure I know what the problem is and if I can fix it before I go replace the hotend or power supply.

Sorry for the long read btw. I'm happy to give more details if needed. Any responses are helpful!

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Update: After opening the bottom part of the PSU, the part with all the screws holding the wires in place, I can confirm the the PSU is not the problem. When I turn the hotend on, the power LED does not turn off and then immediately turn back on, it stays on. This means that the PSU is not suddenly shutting down when under load and then causing the printer to restart. This is kind of annoying, because it means that the problem very well may be the hotend.

⟐ Commented January 05, 2026 at 2:50 MST

More or less what happens is that the print starts off normal, and then the print simply stops at a certain point. This isn't because the filament is caught on anything, I've had this issue for a few months and taken apart a few items of the printer. I'm not sure if this is a settings issue, or if this might be an issue with the hotend, as I had to replace it, and these problems started after a few such changes.

If you have any questions you need me to clarify, I'd really like to solve this. Thanks.

⟐ Commented October 19, 2025 at 2:27 MST

⟐ Answered September 20, 2025 at 14:48 MST

⟐ Answered September 17, 2025 at 5:15 MST

The Motors and their Drivers have been checked, they are ok. I already moved them by the other axes commands using an home made extension cable.

⟐ Commented April 24, 2025 at 15:39 MST

⟐ Answer edited April 15, 2025 at 23:39 MST

I haven’t been able to find an exact pinout, but I want to know if it’s possible to fix a ribbon cabel of that size. And if yes, how can I perform this fix and what tools do I need? (I have a ryobi soldering iron, oscilloscope, multimeter, etc)

⟐ Answered March 25, 2025 at 0:55 MST