Hi, I'm new to 3D printing & have recently purchased a Flashforge Creator Pro. I've been extremely happy with the results but lately the extruders have started clogging up!I read on another forum about using a very thin needle to unblock it whilst heating the extruder to 260 degrees. This has worked well a couple of times while i was using ABS Filament. I've now swapped to PLA Filament & for some reason it has blocked AGAIN & i cant seem to un block it even though the needle doesn't seem to find any blockage inside! Sometimes, a tiny bit of black gunk comes out but it's still blocked! Can anyone offer any advice please? Thanks