Thanks, Marcin. The material is definitely not tangled on the spool.
I did https://support.zort...er-maintenance/ as you suggested. I couldn't unload the material - it's really stuck and I was afraid to pull so hard as to break the filament by pulling. The nozzle was plenty hot (so that's not the problem).
When I took apart the motor assembly (as recommended), it looks as in the photos I'm attaching.
Whatever is stuck, is deep in the nozzle.
Should I just pull as hard as needed until the filament breaks? I think that'd leave whatever's stuck still inside.
After fiddling with the printer for a few hours, I've concluded that it's the nozzle itself that's clogged.
If I remove the nozzle completely, I can feed ABS thru the extruder.
When I put the nozzle back on, nothing comes out no matter what I do.
I suppose there must have been a dust particle or something that blocked the nozzle.
The problem is that the nozzle is filled with PET, so soaking it in acetone isn't going to help any, and I don't have a pin small enough to fit (0.4 mm?).
How can I get a new nozzle quickly? (Colleagues are waiting on prints.) I'm in the USA.