CTC PROBLEM PLEASE HELP I TRYED EVERYTHING

Hi guys, I recently purchased a CTC 3D printer, I was able to print a couple of things then the extruder started to click. I was printing with PLA on the right extruder and I switched over to the left extruder, but then that one started to click as well. When the motor clicks the plastic doesn't come out. Even if I push really hard with the plastic on the top, it still wont stop clicking. I put some vegetable oil in the extuder and that seemed to help but one for a short while. Is there a fix? I also tried different temps but nothing worked. I also cant figure out how to remove the nozzle, it seems like its too tight, and i don't want to break anything. I really want to fix this problem so if anyone can help that would be great. Thanks.