I’m usually the last to learn anything, so this may be the way a lot of you do it. Previously I would heat the nozzle in a vice and then take one of those acupuncture needs and ram it through the nozzle from the top side. Since the needle has a smaller diameter than the nozzle, I figured it had to be leaving some filament behind. So this time I took some scrap filament, heated the nozzle, and pushed the filament in from the top until I could see it extruding from the nozzle. I’m going to leave a foot or so in there until I need to swap nozzles again. Then I’m going to thread the filament up through the hub and give it a print file until it runs out in the usual fashion, then load on some filament from the spool.
If you are still able to push some filament through, then I recommend looking up the cold pull method. I didn’t need it yet on my Bambu printer but on my older printer, it is amazing how much gunk you can recover that way from a nozzle 
Right. I saw that demonstrated. I think I’ll try that on this nozzle with the PLA pigtail.