Problem with a Lulzbot Taz Workhorse

Hi everyone !
I’m new on this forum, but I’ve already 3 FDM 3D printer. I’ve just bought a Lulzbot Taz Workhorse, but I’ve some troubles. When I print a model, the printer makes big balls of pla from time to time, and I don’t know why. To find some solutions, I’ve try to change the nozzle but I’ve always the same troubles. I’ll give you some photo to show you exactly what the printer do.
I print my PLA with normal settings (210°C, 50°C heated bed, 40mm/s printing speed, raft…) I’ve also try different slicer (Cura Lulzbot Edition and Cura 4.5), but I’ve the same troubles with both.
If anyone have an issue or can help me, I’d really appreciate it !
Thanks everybody and have lots of good print !