Actually, you can fix it while printing – but it’s a lot easier if you can unload the filament from the extruder. If you do want to do it “in place”, you’ll have to loosen a lot of filament and then run the spool through the loops to unknot the feed (somewhat like untangling a big bundle of extension cables).
Maybe you can pause the print, home, fix your issue (which includes backing out the filament, fixing the tangle, reloading the filament) extrude a bit of filament, remove that string and the resume the print. I usually do this with the problem being bed adhesion issues.
Thanks @NathanielStenzel but I’ve tried “Hot Swapping” before and it doesn’t work too well with my “cheap printer”.
@Scottie_D369 oh well. I tried. To be honest, I would not be able to pause, fix, resume without Octoprint or Pronterface. Those are the only programs that I use for feeding gcode to my printer.
How about pictures Scottie? They say for more than anything else.