So I bought an E3d all metal hotend a couple months ago, and it was running great until I somehow had it ooze PLA everywhere. Just...everywhere. The entire heater block, nozzle, and heatbreak were covered in PLA. However! Since the whole thing is metal, no PEEK or teflon in sight, I took as much of it apart as I could and tossed it into my oven on a sheet of foil, and set the oven to self clean.
Self clean runs at 500c.
Long story short, I'll need a new heater core, but what was solid PLA gumming up everything in the hotend is now a layer of fine ash, which I'll be rinsing away.
NOTE: This did make my apartment smell like burning plastic for an hour, I had to open all of my windows.