X1C/P1S/Bambu Studio: Recently I had a print fail because filament broke during retraction on a filament change. It turned out that the filament had broken just a few centimeters from the print head. I am wondering if it would be possible to force a load filament operation and push the broken piece through rather than abort a 5 hour print. Perhaps by pushing the new filament through the external spool tube?
Don’t know if this will help, but I have run out of filament of a given color, and I am able to just insert another spool of filament in the same AMS slot, and gently push the filament into the tube and the AMS will grab the filament and continue printing. I have done this several times successfully. Hope this helps you out.
Thanks for the idea. I tried that. I pulled the filament out of the ams and tried to start another spool but this wasn’t a ran-out-of-filament situation. The ams was trying to retract the filament from the extruder so it could switch colors. The retraction failed since once the filament broke there was no way for the ams to pull the filament from the extruder. I opened the top of the printer, pulled the filament from the extruder and from the bowden tube. Put the tube back in the extruder. The ams continued with the filament change but the extruder purged filament all over the bed plate and print. But if I could have just told the printer to flush the filament into the poop chute until the break was cleared then do a retraction this failure could have been recovered. The system knew the retraction failed because the AMS was rewinding filament but the print head still detected filament. There was no filament in the AMS buffer.
So the system could have known the break was between the filament buffer in the back of the machine and the tool head. Perfect situation for a purge. In fact, the printer told me that the filament was probably broken. But I couldn’t send the load filament command to the printer. I could on the A1 Mini by doing a load filament command from the printer menu. I think that maybe should also be allowed in the x1c and p1 series - if there is no filament in the buffer but there is in the extruder. In fact, the printer could offer an informational message stating that the filament appears to be broken near the extruder, would the user like to attempt a filament purge? Then just like the A1 Mini allow the user to keep purging until they see the new color coming out the nozzle. This could have saved a 4 hour investment in the print to that point.
All this was on the X1C. I am assuming the same situation could arise on the P1S.
Admittedly, this is an edge case, filament broke between the buffer and extruder during a color change filament retraction. If it had broken between the buffer and the AMS then the buffer would know there is filament there. Then we remove the bowden tube from the buffer and pull the filament out of the printer since it was already cut at the extruder and (probably) also pull it out of the AMS. Then the color change could proceed normally.
But maybe this is too much responsibility for your typical X1C/P1S user? I don’t mean that at all snarky. Bambu printers just work because of solid engineering that takes care of new users and makes them feel experienced and competent every time a print completes. Maybe this is too much user fiddling and the very occasional edge case print failure goes with the territory of their audience.
I love my Bambu printers. Nothing about this situation makes me wish I had bought something else. This is just a thought on how I might have saved four hours and some filament. In case a Bumbu Lab engineer sees this. 
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