Try to tape both heatsink holes on the botom side of Smart Extruder with simple painters tape. Attach extruder to the printer, and start normal Filament Loading process, try to use a little bit of force when pushing filament into the hole with one hand, and use another one to hold it firmly attached to Carriage. This way Extruder will produce more heat and filament should release itself inside Smart Extruder. Hope it will help you. Good luck!
I know this is an older post, but I thought I'd try to help incase some one new looks at this in the future. This is how I unclog and clean our old extruders.
Great help on the video. I agree 5th gen is a lot less desirable for me. I have a 2X and a Replicator 5th and I favor the 2X because it is so easy to fix anything that gets broken. The 5th gen is too Crapple like. I still love the large build area and the Smart Extruder+ sometimes is too smart for itself making it look stupid. But this is just all learning, in time the 5th will be just like the 2X.