I’ve run into the same issue about three times recently with my P1S. During a print, after several successful filament changes through the AMS, the printer suddenly develops what looks like a clog (photo attached). When this happens, the next filament tries to load but can’t, and the AMS sends it back.
This has happened with both white and orange PLA. The orange spool is Bambu Lab PLA (500g) that came with the P1S Combo. I bought the printer in August 2025, and the filament was stored in a vacuum bag with desiccant until I opened it for this project.
In previous occurrences, I was able to clear the blockage by heating the hotend to 250°C and pushing it through with a No‑Clog tool from Amazon. The hotend is a Microswiss unit that has worked flawlessly for about six months.
At this point I’m not sure what’s causing these sudden clogs or failed filament loads. Any suggestions would be appreciated.
It’s possible that the different thermal behavior of that hotend is allowing heat creep during filament change.
If you have a caliper, check the filament diameter at the point where there’s an issue, that will confirm heat creep, otherwise you could just hold some of the “regular” filament up next to it to do a visual comparison.
Is your door open during the print? It should be, and try having the lid off, as well
If those aren’t enough, you may need to modify some settings, either cooling or the filament change gcode section of your printer profile in Bambu Studio.
The updated hotend is made by Microswiss and is hardened steel.
I decided to replace the hotend with the original Bambu Lab 0.4 stainless steel; then load some filament to check. I switched the P1S hotend back to stainless. After the hotend flushed out the small amount of filament left inside the tip, the P1S began to load the filament. I could see where the filament made it to the hotend. After a slight pause the filament did not load and returned to the AMS, the repeated and failing to load over and over until I cut the power. Then I tried with a different filament an received the same results.
I have a filament won’t load! There was not an error message.
You probably had to do this as part of the previous work, but maybe double check the health of the PTFE connection to the top of the toolhead’s pneumatic fitting. If it’s bit up and the teeth are tearing thru the ptfe biting into the filament, it can get it stuck before the extruder gets to bite. Don’t remove too much material or youll need to redo the whole line, but you can generally trim the roughly bitten 1/4” of PTFE off and reset without running into “too short of a tube” style problems. Use one of those 90degree-cut tools if you have it.
Then I removed the extruder, opened the cover and found a small piece of filament inside. It was perhaps 10-15mm long, curled and so very thin I almost overlooked it. I reassembled the extruder and installed it back into the P1S. Ran two tests this morning, including the filament in question, and had no issues!
