20 hours into a 23 hour print and “extruder clog” message pops up, confirmed by green light on extruder feedback on the Device tab…
I know how to fix jams / clogs, but how does one do it without losing the print job???!
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I suppose it has paused the print. You could try to disassemble the print head while it’s paused. You can pop off the cover and unscrew the hotend from the extruder while it’s hot without unplugging the cables (important, or otherwise this will shut down for safety reasons, namely thermal runaway).
Before you do that make sure to cut the filament using the lever on the print head.
The upper part should be cool enough to touch, so you can take it out. Make sure not to put your fingers into the 30mm fan on there and that it doesn’t get caught when you leave the hotend hanging. That’s not a pleasant sound, trust me 
When you took it apart you should be able to check if it is the extruder or the hotend which is clogged.
When it’s the hotend, I’d recommend first poking in the needle into the nozzle to push out any stuck filament from the bottom to the top and then manually try to “extrude” some fresh filament while its still apart. Then pull the rest of the filament out again and reassemble it. Then screw the hotend back on and now extrude some filament using the extrude function on the display. Then change the temperature to some low value (80 to 100 degrees for PLA) and wait for the nozzle to cool down. Afterwards pull on the filament and retract it on the display at the same time, so a cold pull is performed. You can do this multiple times to make sure it’s clean.
Afterwards set the temperature back to where it was before.
I would not recommend doing cold pulls with the hotend unscrewed or otherwise you might damage the cables or the daughter board connectors.
When the extruder is the problem, go ahead and take that one apart. I’d still do the cold pull steps then, just to be safe.
I’ve done this before and it worked.
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I would not recommend working on the hot end with the printer running. It is too easy to fry the circuit board. (There are multiple posts on that.) Instead, you can turn off the printer, work on it, and then turn it back on. I have tested resume from loss of power and it worked fine.
The issue with that is only that you can’t unclog the nozzle if filament is stuck in there and it being cold.
Of course this must be done with caution, when there is no other way. I had such a case once where filament was slightly too wide and stuck in the nozzle and was cut off flush with the nozzle. It was too wide to be pushed in further and could only be removed with the needle from the bottom when the hotend was disconnected from the extruder. The needle could only be i serted while the nozzle was hot.
When it’s just the extruder then it can be done in the off state.
youtu.be/s0FWnHFi7z0
I found a video that solve the “clog pause” elegantly, it uses an unclog pin tool from flashforge to unclog the nozzle from top to down without disassemble anything (could be dangerous), and without powering off the printer. The tool is just a 1.5mm diameter steel stick.
Another way is to power off the printer when at pause, then swap the hotend or extruder with new one, turn it back on, the printing will resume from loss of power.
You mean Auto-recovery from step loss?
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I got the same message. I troubleshooted from the simplest to the most complex reasons. My solution was to check the AMS first. Luckily, it was a simple matter of the filament being tangled when the color filament was switched. I didn’t have to mess with any complex fixes.
Those are two different things:
Power loss recovery: lets you resume a print job after power is lost (or tuned off) to printer.
Auto step loss recovery: if the tool head does not execute a move as expected, for example something interfered with the tool head and preventing it from moving, it will rehome by going to the corner to reorient itself and resume printing from the spot the step loss was detected.
I literally did what you’ve proposed. I’ve turned off the printer first. It was intense to work in such confined space not mess up the prints after 7 hours of print but I managed to remove the hot-end and the extruded and remedied the situation. After I’ve turn-on the printer It prompted for me to resume, it worked haha.
The tutorials I’ve used to remove things are:
https://wiki.bambulab.com/en/x1/troubleshooting/extruder-clog
https://wiki.bambulab.com/en/x1/troubleshooting/nozzle-clog
Thanks!